TY - JOUR AB - From organs to subcellular organelles, trace element (TE) homeostasis is fundamental for many physiological processes. While often overlooked in early stages, manifested TE disbalance can have severe health consequences, particularly in the context of aging or pathological conditions. Monitoring TE concentrations at the mitochondrial level could identify organelle-specific imbalances, contributing to targeted diagnostics and a healthier aging process. However, mitochondria isolation from frozen tissue is challenging, as it poses the risk of TE losses from the organelles due to cryodamage, but would significantly ease routine laboratory work. To address this, a novel method to isolate an enriched mitochondria fraction (EMF) from frozen tissue was adapted from already established protocols. Validation of manganese (Mn), iron (Fe), and copper (Cu) quantification via inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) showed sufficiently low quantification limits for EMF TE analysis. Successful mitochondrial enrichment from frozen liver samples was confirmed via immunoblots and transmission electron microscopy (TEM) revealed sufficient structural integrity of the EMFs. No significant differences in EMF TEs between frozen and fresh tissue were evident for Mn and Cu and only slight decreases in EMF Fe. Consequently, EMF TEs were highly comparable for isolates from both tissue states. In application, this method effectively detected dietary differences in EMF Fe of a murine feeding study and identified the disease status in a Wilson disease rat model based on drastically increased EMF Cu. In summary, the present method is suitable for future applications, facilitating sample storage and high-throughput analyses of mitochondrial TEs. AU - Heinze, T.* AU - Ebert, F.* AU - Ott, C.* AU - Nagel, J.* AU - Eberhagen, C. AU - Zischka, H. AU - Schwerdtle, T.* C1 - 71051 C2 - 55993 TI - Subzero project: Comparing trace element profiles of enriched mitochondria fractions from frozen and fresh liver tissue. JO - Anal. Bioanal. Chem. PY - 2024 SN - 1618-2642 ER - TY - JOUR AB - The reliability of analytical results is critical and indispensable when applied in regulated environments such as the pharmaceutical industry. Therefore, analytical workflows must be validated. However, validation guidelines are often designed for quantitative targeted analysis and rarely apply to qualitative untargeted approaches. In this study, we employ a risk assessment approach to identify critical parameters which might influence the qualitative results derived by online derivatisation - comprehensive two-dimensional gas chromatography coupled to a high-resolution time-of-flight mass spectrometer (GC × GC-HR-ToF-MS) for the analysis of the active pharmaceutical ingredient (API) sodium bituminosulfonate (SBS). To show the complexity and feasibility of such an approach, we focus on investigating three potential risk factors: sample preparation, vapourability, and the thermal stability of sulfonates. Through the individual evaluation of these potential risk factors due to the application of sample preparation approaches and thermal gravimetric analysis (TGA), we demonstrate the high derivatisation efficiency and repeatability of the online derivatisation method and confirm the absence of derivatisation-induced side reactions. In addition, we also show the potential thermal instability of an incompletely derivatised API. To address the limitation of these individual assessments, we applied a holistic evaluation step with negative electrospray ionisation Fourier transform ion cyclotron resonance mass spectrometry (ESI( -) FT-ICR MS) as an orthogonal technique. This confirms that most of the API is detected via the presented GC-based method. Thereby, we demonstrated the practical feasibility of the risk assessment-based approach to ensure the validity of the qualitative data for a complex untargeted method. AU - Schwalb, L. AU - Tiemann, O.* AU - Käfer, U. AU - Rüger, C.P.* AU - Gröger, T.M. AU - Zimmermann, R. C1 - 69055 C2 - 53833 CY - Tiergartenstrasse 17, D-69121 Heidelberg, Germany SP - 1033–1045 TI - Applying a risk assessment guided evaluation for verifying comprehensive two-dimensional gas chromatography to analyse complex pharmaceuticals. JO - Anal. Bioanal. Chem. VL - 416 PB - Springer Heidelberg PY - 2024 SN - 1618-2642 ER - TY - JOUR AB - The SARS-CoV-2 pandemic has shown the importance of rapid and comprehensive diagnostic tools. While there are numerous rapid antigen tests available, rapid serological assays for the detection of neutralizing antibodies are and will be needed to determine not only the amount of antibodies formed after infection or vaccination but also their neutralizing potential, preventing the cell entry of SARS-CoV-2. Current active-virus neutralization assays require biosafety level 3 facilities, while virus-free surrogate assays are more versatile in applications, but still take typically several hours until results are available. To overcome these disadvantages, we developed a competitive chemiluminescence immunoassay that enables the detection of neutralizing SARS-CoV-2 antibodies within 7 min. The neutralizing antibodies bind to the viral receptor binding domain (RBD) and inhibit the binding to the human angiotensin-converting enzyme 2 (ACE2) receptor. This competitive binding inhibition test was characterized with a set of 80 samples, which could all be classified correctly. The assay results favorably compare to those obtained with a more time-intensive ELISA-based neutralization test and a commercial surrogate neutralization assay. Our test could further be used to detect individuals with a high total IgG antibody titer, but only a low neutralizing titer, as well as for monitoring neutralizing antibodies after vaccinations. This effective performance in SARS-CoV-2 seromonitoring delineates the potential for the test to be adapted to other diseases in the future. AU - Klüpfel, J.* AU - Paßreiter, S.* AU - Rumpf, M.P.* AU - Christa, C. AU - Holthoff, H.P.* AU - Ungerer, M.* AU - Lohse, M.J.* AU - Knolle, P.* AU - Protzer, U. AU - Elsner, M.* AU - Seidel, M.* C1 - 66594 C2 - 53223 SP - 391-404 TI - Automated detection of neutralizing SARS-CoV-2 antibodies in minutes using a competitive chemiluminescence immunoassay. JO - Anal. Bioanal. Chem. VL - 415 IS - 3 PY - 2023 SN - 1618-2642 ER - TY - JOUR AB - The European pharmacopeia provides analytical methods for the chemical characterization of active pharmaceutical ingredients (APIs). However, the complexity of some APIs exceeds the limitations of the currently prevailing physicochemical methods. Sodium bituminosulfonate (SBS) is described by the collection of key parameters of generalizing criteria such as dry matter, sulfur and sodium content, and neutrality, but techniques to unravel the complexity on a molecular level are lacking. We present a study based on online derivatization with tetramethylammonium hydroxide in combination with comprehensive two-dimensional gas chromatography coupled to an electron ionization high-resolution time-of-flight mass spectrometer (GC × GC-HR-ToF–MS) for the chemical description of SBS as well as its process intermediates. The application of GC × GC allowed the comprehensive description of the chemical components in the API and the process intermediates for the first time. Furthermore, it was possible to classify peaks regarding their elemental and structural composition based on accurate mass information, elution behavior, and mass fragmentation pattern. This work demonstrates not only the general applicability, advantages but also limitations of GC × GC for the characterization of APIs for complex drugs. Graphical Abstract: [Figure not available: see fulltext.] AU - Schwalb, L. AU - Tiemann, O.* AU - Käfer, U. AU - Gröger, T.M. AU - Rüger, C.P.* AU - Gayko, G.* AU - Zimmermann, R. C1 - 66759 C2 - 53294 TI - Analysis of complex drugs by comprehensive two-dimensional gas chromatography and high-resolution mass spectrometry: Detailed chemical description of the active pharmaceutical ingredient sodium bituminosulfonate and its process intermediates. JO - Anal. Bioanal. Chem. PY - 2022 SN - 1618-2642 ER - TY - JOUR AB - In the face of the COVID-19 pandemic, the need for rapid serological tests that allow multiplexing emerged, as antibody seropositivity can instruct about individual immunity after an infection with SARS-CoV-2 or after vaccination. As many commercial antibody tests are either time-consuming or tend to produce false negative or false positive results when only one antigen is considered, we developed an automated, flow-based chemiluminescence microarray immunoassay (CL-MIA) that allows for the detection of IgG antibodies to SARS-CoV-2 receptor-binding domain (RBD), spike protein (S1 fragment), and nucleocapsid protein (N) in human serum and plasma in less than 8 min. The CoVRapid CL-MIA was tested with a set of 65 SARS-CoV-2 serology positive or negative samples, resulting in 100% diagnostic specificity and 100% diagnostic sensitivity, thus even outcompeting commercial tests run on the same sample set. Additionally, the prospect of future quantitative assessments (i.e., quantifying the level of antibodies) was demonstrated. Due to the fully automated process, the test can easily be operated in hospitals, medical practices, or vaccination centers, offering a valuable tool for COVID-19 serosurveillance. Graphical abstract. AU - Klüpfel, J.* AU - Koros, R.C.* AU - Dehne, K.* AU - Ungerer, M.* AU - Würstle, S.* AU - Mautner, J. AU - Feuerherd, M. AU - Protzer, U. AU - Hayden, O.* AU - Elsner, M.* AU - Seidel, M.* C1 - 62031 C2 - 50604 CY - Tiergartenstrasse 17, D-69121 Heidelberg, Germany SP - 5619-5632 TI - Automated, flow-based chemiluminescence microarray immunoassay for the rapid multiplex detection of IgG antibodies to SARS-CoV-2 in human serum and plasma (CoVRapid CL-MIA). JO - Anal. Bioanal. Chem. VL - 413 IS - 22 PB - Springer Heidelberg PY - 2021 SN - 1618-2642 ER - TY - JOUR AB - The stability of lipids and other metabolites in human body fluids ranges from very stable over several days to very unstable within minutes after sample collection. Since the high-resolution analytics of metabolomics and lipidomics approaches comprise all these compounds, the handling of body fluid samples, and thus the pre-analytical phase, is of utmost importance to obtain valid profiling data. This phase consists of two parts, sample collection in the hospital (“bedside”) and sample processing in the laboratory (“bench”). For sample quality, the apparently simple steps in the hospital are much more critical than the “bench” side handling, where (bio)analytical chemists focus on highly standardized processing for high-resolution analysis under well-controlled conditions. This review discusses the most critical pre-analytical steps for sample quality from patient preparation; collection of body fluids (blood, urine, cerebrospinal fluid) to sample handling, transport, and storage in freezers; and subsequent thawing using current literature, as well as own investigations and practical experiences in the hospital. Furthermore, it provides guidance for (bio)analytical chemists to detect and prevent potential pre-analytical pitfalls at the “bedside,” and how to assess the quality of already collected body fluid samples. A knowledge base is provided allowing one to decide whether or not the sample quality is acceptable for its intended use in distinct profiling approaches and to select the most suitable samples for high-resolution metabolomics and lipidomics investigations. Graphical abstract: [Figure not available: see fulltext.] AU - Lehmann, R. C1 - 62380 C2 - 50694 CY - Tiergartenstrasse 17, D-69121 Heidelberg, Germany SP - 5567-5585 TI - From bedside to bench—practical considerations to avoid pre-analytical pitfalls and assess sample quality for high-resolution metabolomics and lipidomics analyses of body fluids. JO - Anal. Bioanal. Chem. VL - 413 IS - 22 PB - Springer Heidelberg PY - 2021 SN - 1618-2642 ER - TY - JOUR AB - Chromatographic retention time information is valuable, orthogonal information to MS and MS/MS data that can be used in metabolite identification. However, while comparison of MS data between different instruments is possible to a certain degree, retention times (RTs) can vary extensively, even when nominally the same phase system is used. Different factors such as column dead volumes, system extra column volume, and gradient dwell volume can influence absolute retention times. Retention time indexing (RTI), routinely employed in gas chromatography (e.g., Kovats index), allows compensation for deviations in experimental conditions. Different systems have been reported for RTI in liquid chromatography, but none of them have been applied to metabolomics to the same extent as they have with GC. Recently, a more universal RTI system has been reported based on a homologous series of N-alkylpyridinium sulfonates (NAPS). These reference standards ionize in both positive and negative ionization modes and are UV-active. We demonstrate the NAPS can be used for retention time indexing in reversed-phase-liquid chromatography-mass spectrometry (RP-LC–MS)–based metabolomics. Having measured >500 metabolite standards and varying flow rate and column dimension, we show that conversion of RT to retention indices (RI) substantially improves comparability of retention information and enables to use of RI for metabolite annotation and identification. [Figure not available: see fulltext.]. AU - Stoffel, R. AU - Quilliam, M.A.* AU - Hardt, N.* AU - Fridstrom, A.* AU - Witting, M. C1 - 63840 C2 - 51685 CY - Tiergartenstrasse 17, D-69121 Heidelberg, Germany TI - N-Alkylpyridinium sulfonates for retention time indexing in reversed-phase-liquid chromatography-mass spectrometry–based metabolomics. JO - Anal. Bioanal. Chem. PB - Springer Heidelberg PY - 2021 SN - 1618-2642 ER - TY - JOUR AB - Lipid identification is one of the current bottlenecks in lipidomics and lipid profiling, especially for novel lipid classes, and requires multidimensional data for correct annotation. We used the combination of chromatographic and ion mobility separation together with data-independent acquisition (DIA) of tandem mass spectrometric data for the analysis of lipids in the biomedical model organism Caenorhabditis elegans. C. elegans reacts to harsh environmental conditions by interrupting its normal life cycle and entering an alternative developmental stage called dauer stage. Dauer larvae show distinct changes in metabolism and morphology to survive unfavorable environmental conditions and are able to survive for a long time without feeding. Only at this developmental stage, dauer larvae produce a specific class of glycolipids called maradolipids. We performed an analysis of maradolipids using ultrahigh performance liquid chromatography-ion mobility spectrometry-quadrupole-time of flight-mass spectrometry (UHPLC-IM-Q-ToFMS) using drift tube ion mobility to showcase how the integration of retention times, collisional cross sections, and DIA fragmentation data can be used for lipid identification. The obtained results show that combination of UHPLC and IM separation together with DIA represents a valuable tool for initial lipid identification. Using this analytical tool, a total of 45 marado- and lysomaradolipids have been putatively identified and 10 confirmed by authentic standards directly from C. elegans dauer larvae lipid extracts without the further need for further purification of glycolipids. Furthermore, we putatively identified two isomers of a lysomaradolipid not known so far. AU - Witting,M. AU - Schmidt, U.* AU - Knölker, H.J.* C1 - 61307 C2 - 50122 CY - Tiergartenstrasse 17, D-69121 Heidelberg, Germany SP - 2091–2102 TI - UHPLC-IM-Q-ToFMS analysis of maradolipids, found exclusively in Caenorhabditis elegans dauer larvae. JO - Anal. Bioanal. Chem. VL - 413 PB - Springer Heidelberg PY - 2021 SN - 1618-2642 ER - TY - JOUR AB - A prior method of mass labeling ketone-/aldehyde-containing species in natural dissolved organic matter (DOM) is further developed and applied. This application involved the treatment of Suwannee River fulvic acid (SRFA) with increasing concentrations of sodium borodeuteride (NaBD4), followed by detection of reduced species via negative mode electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FTICR MS). The extent of reduction, as determined by ESI FTICR MS, resulting from increasing concentrations of NaBD4 correlated well with changes in the absorption and emission spectra of the corresponding untreated and borodeuteride-reduced samples, providing evidence that ketone/aldehyde functional groups contribute substantially to the bulk optical properties of SRFA. Furthermore, the differences in the reactivity and abundance of ketone-/aldehyde-containing species for various regions in Van Krevelen plots were revealed, thus showing how this mass labeling method can be used to provide more detailed structural information about components within complex DOM samples than that provided by the determination and analysis of molecular formulae alone. AU - Bianca, M.R.* AU - Baluha, D.R.* AU - Gonsior, M.* AU - Schmitt-Kopplin, P. AU - Del Vecchio, R.* AU - Blough, N.V.* C1 - 57864 C2 - 48165 CY - Tiergartenstrasse 17, D-69121 Heidelberg, Germany SP - 1441-1451 TI - Contribution of ketone/aldehyde-containing compounds to the composition and optical properties of Suwannee River fulvic acid revealed by ultrahigh resolution mass spectrometry and deuterium labeling. JO - Anal. Bioanal. Chem. VL - 412 IS - 6 PB - Springer Heidelberg PY - 2020 SN - 1618-2642 ER - TY - JOUR AB - Soyasaponins are oleanene-type triterpenoid saponins, naturally occurring in many edible plants that have attracted a great deal of attention for their role in preventing chronic diseases. The aim of this study was to establish the distribution and the content of soyasaponins in 21 ecotypes of Fagioli di Sarconi beans (Phaseolus vulgaris, Leguminosae). High-performance reversed-phase liquid chromatography (RPLC) with positive electrospray ionization (ESI(+)) and Fourier transform ion cyclotron resonance (FTICR) mass spectrometry (MS) in conjunction with infrared multiphoton dissociation (IRMPD) was applied for the unambiguous identification of soyasaponins Ba (m/z 959.5213, [C48H79O19](+)), Bb (m/z 943.5273, [C48H79O18](+)), Bd (m/z 957.5122, [C48H77O19](+)), and Be (m/z 941.5166, [C48H77O18](+)), which are the only commercially available reference standards. In addition, the several diagnostic product ions generated by IRMPD in the ICR-MS cell allowed us the putative identification of soyasaponins Bb' (m/z 797.4680, [C42H69O14](+)), alpha g (m/z 1085.5544, [C54H85O22](+)), beta g (m/z 1069.5600, [C54H85O21](+)), and gamma g (m/z 923.5009, [C48H75O17](+)), establishing thus their membership in the soyasaponin group. Quantitative and semiquantitative analysis of identified soyasaponins were also performed by RPLC-ESI(+) FTICR-MS; the total concentration levels were found ranging from 83.6 +/- 9.3 to 767 +/- 37 mg/kg. In vitro hypoglycemic outcomes of four soyasaponin standards were evaluated; significant inhibitory activities were obtained with IC50 values ranging from 1.5 +/- 0.1 to 2.3 +/- 0.2 mu g/mL and 12.0 +/- 1.1 to 29.4 +/- 1.4 mu g/mL for alpha-glucosidase and alpha-amylase, respectively. This study represents the first detailed investigation on the antidiabetic activity of bioactive constituents found in Fagioli di Sarconi beans. AU - Bianco, G.* AU - Pascale, R.* AU - Carbone, C.F.* AU - Acquavia, M.A.* AU - Cataldi, T.R.I.* AU - Schmitt-Kopplin, P. AU - Buchicchio, A.* AU - Russo, D.* AU - Milella, L.* C1 - 52652 C2 - 44095 CY - Heidelberg SP - 1561–1569 TI - Determination of soyasaponins in Fagioli di Sarconi beans (Phaseolus vulgaris L.) by LC-ESI-FTICR-MS and evaluation of their hypoglycemic activity. JO - Anal. Bioanal. Chem. VL - 410 IS - 5 PB - Springer Heidelberg PY - 2018 SN - 1618-2642 ER - TY - JOUR AB - Mass spectrometry imaging (MSI) has provided many results with translational character, which still have to be proven robust in large patient cohorts and across different centers. Although formalin-fixed paraffin-embedded (FFPE) specimens are most common in clinical practice, no MSI multicenter study has been reported for FFPE samples. Here, we report the results of the first round robin MSI study on FFPE tissues with the goal to investigate the consequences of inter-and intracenter technical variation on masking biological effects. A total of four centers were involved with similar MSI instrumentation and sample preparation equipment. A FFPE multi-organ tissue microarray containing eight different types of tissue was analyzed on a peptide and metabolite level, which enabled investigating different molecular and biological differences. Statistical analyses revealed that peptide intercenter variation was significantly lower and metabolite intercenter variation was significantly higher than the respective intracenter variations. When looking at relative univariate effects of mass signals with statistical discriminatory power, the metabolite data was more reproducible across centers compared to the peptide data. With respect to absolute effects (cross-center common intensity scale), multivariate classifiers were able to reach on average > 90% accuracy for peptides and > 80% for metabolites if trained with sufficient amount of cross-center data. Overall, our study showed that MSI data from FFPE samples could be reproduced to a high degree across centers. While metabolite data exhibited more reproducibility with respect to relative effects, peptide data-based classifiers were more directly transferable between centers and therefore more robust than expected. AU - Buck, A. AU - Heijs, B.* AU - Beine, B.* AU - Schepers, J.* AU - Cassese, A.* AU - Heeren, R.M.A.* AU - McDonnell, L.A.* AU - Henkel, C.* AU - Walch, A.K. AU - Balluff, B.* C1 - 53865 C2 - 45042 CY - Tiergartenstrasse 17, D-69121 Heidelberg, Germany SP - 5969–5980 TI - Round robin study of formalin-fixed paraffin-embedded tissues in mass spectrometry imaging. JO - Anal. Bioanal. Chem. VL - 410 IS - 23 PB - Springer Heidelberg PY - 2018 SN - 1618-2642 ER - TY - JOUR AB - Capillary zone electrophoresis (CZE) based on electrophoretic mobility in the liquid phase and ion mobility spectrometry (IMS) based on mobilities in the gas phase are both powerful techniques for the separation of complex samples. Protein glycosylation is one of the most common post-translational modifications associated with a wide range of biological functions and human diseases. Due to their high structural variability, the analysis of glycans still represents a challenging task. In this work, the first on-line coupling of CZE with drift tube ion mobility-mass spectrometry (DTIM-MS) has been perfomed to further improve separation capabilities for the analysis of native and 8-aminopyrene-1,3,6-trisulfonic acid (APTS)-labeled N-glycans. In this way, a complexity of glycan signals was revealed which could not be resolved by these techniques individually, shown for both native and APTS-labeled glycans. Each individual glycan signal separated in CZE exhibited an unexpectedly high number of peaks observed in the IMS dimension. This observation could potentially be explained by the presence of isomeric forms, including different linkages, and/or gas-phase conformers. In addition, the type of sialic acid attached to glycans has a significant impact on the obtained drift time profile. Furthermore, the application of alpha 2-3 neuraminidase enabled the partial assignment of peaks in the arrival time distribution considering their sialic acid linkages (alpha 2-3/alpha 2-6). This work is a showcase for the high potential of CZE-DTIM-MS, which is expected to find various applications in the future. AU - Jooß, K. AU - Meckelmann, S.W.* AU - Klein, J.* AU - Schmitz, O.J.* AU - Neusüß, C.* C1 - 54973 C2 - 46000 CY - Tiergartenstrasse 17, D-69121 Heidelberg, Germany SP - 6255-6264 TI - Capillary zone electrophoresis coupled to drift tube ion mobility-mass spectrometry for the analysis of native and APTS-labeled N-glycans. JO - Anal. Bioanal. Chem. VL - 411 IS - 24 PB - Springer Heidelberg PY - 2018 SN - 1618-2642 ER - TY - JOUR AB - Electromigration separation techniques often demand certain compounds in the electrolyte to achieve the required selectivity and efficiency. These compounds, including the electrolyte itself, ampholytes, polymeric compounds for sieving, complexing agents, tensides, etc. are often non-volatile. Thus, interference with the electrospray ionization process is a common issue, impeding direct coupling of such electrolyte systems to mass spectrometry. Still, several options exist to obtain mass spectra after separation, including offline fractionation, alternative ionization, dilution, or the change to volatile constituents. In the first part of this article, these methods are discussed. However, all of these options are a compromise of separation performance and sensitivity of mass spectrometric detection. Two-dimensional capillary electrophoresis-mass spectrometry (CE-CE-MS) systems represent a promising alternative to the aforementioned challenges, as they allow the use of existing methods with best separation performance in combination with sensitive mass characterization. In this context, the second part of this article is dedicated to the advantages, limitations, and applications of this approach. Finally, an outlook towards future developments is given. AU - Schlecht, J.* AU - Jooß, K. AU - Neusüß, C.* C1 - 53836 C2 - 45066 CY - Tiergartenstrasse 17, D-69121 Heidelberg, Germany SP - 6353-6359 TI - Two-dimensional capillary electrophoresis-mass spectrometry (CE-CE-MS): Coupling MS-interfering capillary electromigration methods with mass spectrometry. JO - Anal. Bioanal. Chem. VL - 410 IS - 25 PB - Springer Heidelberg PY - 2018 SN - 1618-2642 ER - TY - JOUR AB - We examined the potential of stable-isotope Raman microspectroscopy (SIRM) for the evaluation of differently enriched C-13-labeled humic acids as model substances for soil organic matter (SOM). The SOM itself can be linked to the soil water holding capacity. Therefore, artificial humic acids (HA) with known isotopic compositions were synthesized and analyzed by means of SIRM. By performing a pregraphitization, a suitable analysis method was developed to cope with the high fluorescence background. Results were verified against isotope ratio mass spectrometry (IRMS). The limit of quantification was 2.1 x 10(-1 13)C/C (tot) for the total region and 3.2 x 10(-2 13)C/C (tot) for a linear correlation up to 0.25 C-13/C (tot). Complementary nanoscale secondary ion mass spectrometry (NanoSIMS) analysis indicated small-scale heterogeneity within the dry sample material, even though-owing to sample topography and occurring matrix effects-obtained values deviated in magnitude from those of IRMS and SIRM. Our study shows that SIRM is well-suited for the analysis of stable isotope-labeled HA. This method requires no specific sample preparation and can provide information with a spatial resolution in the micrometer range. AU - Wiesheu, A.C.* AU - Brejcha, R. AU - Mueller, C.W.* AU - Kögel-Knabner, I.* AU - Elsner, M. AU - Niessner, R.* AU - Ivleva, N.P.* C1 - 51724 C2 - 43464 CY - Heidelberg SP - 923–931 TI - Stable-isotope Raman microspectroscopy for the analysis of soil organic matter. JO - Anal. Bioanal. Chem. VL - 410 IS - 3 PB - Springer Heidelberg PY - 2018 SN - 1618-2642 ER - TY - JOUR AB - Two analytical separation methods-size-exclusion chromatography and asymmetrical flow field-flow fractionation-were implemented to evaluate the integrity of the colloidal composition of Chardonnay white wine and the impact of pressing and fermentations on the final macromolecular composition. Wine chromophoric colloidal matter, representing UV-visible-absorbing wine macromolecules, was evaluated by optical and structural measurements combined with the description of elution profiles obtained by both separative techniques. The objective of this study was to apply these two types of fractionation on a typical Chardonnay white wine produced in Burgundy and to evaluate how each of them impacted the determination of the macromolecular chromophoric content of wine. UV-visible and fluorescence measurements of collected fractions were successfully applied. An additional proteomic study revealed that grape and microorganism proteins largely impacted the composition of chromophoric colloidal matter of Chardonnay wines. Asymmetrical flow field-flow fractionation appeared to be more reliable and less invasive with respect to the native chemical environment of chromophoric wine macromolecules, and hence is recommended as a tool to fractionate chromophoric colloidal matter in white wines. Graphical Abstract An innovative macromolecular separation method based on Asymmetrical Flow Field-Flow Fractionation was developed to better control colloidal dynamics across Chardonnay white winemaking. AU - Coelho, C.* AU - Parot, J.* AU - Gonsior, M.* AU - Nikolantonaki, M.* AU - Schmitt-Kopplin, P. AU - Parlanti, E.* AU - Gougeon, R.D.* C1 - 50532 C2 - 42505 CY - Heidelberg SP - 2757-2766 TI - Asymmetrical flow field-flow fractionation of white wine chromophoric colloidal matter. JO - Anal. Bioanal. Chem. VL - 409 IS - 10 PB - Springer Heidelberg PY - 2017 SN - 1618-2642 ER - TY - JOUR AB - Capillary zone electrophoresis (CZE) is a powerful tool that is progressively being applied for the separation of monoclonal antibody (mAb) charge variants. Mass spectrometry (MS) is the desired detection method concerning identification of mAb variants. In biopharmaceutical applications, there exist optimized and validated electrolyte systems for mAb variant quantification. However, these electrolytes interfere greatly with the electrospray ionization (ESI) process. Here, a heart-cut CZE–CZE–MS setup with an implemented mechanical four-port valve interface was developed that used a generic ε-aminocaproic acid based background electrolyte in the first dimension and acetic acid in the second dimension. Interference-free, highly precise mass data (deviation less than 1 Da) of charge variants of trastuzumab, acting as model mAb system, were achieved. The mass accuracy obtained (low parts per million range) is discussed regarding both measured and calculated masses. Deamidation was detected for the intact model antibody, and related mass differences were significantly confirmed on the deglycosylated level. The CZE–CZE–MS setup is expected to be applicable to a variety of antibodies and electrolyte systems. Thus, it has the potential to become a compelling tool for MS characterization of antibody variants separated in ESI-interfering electrolytes. AU - Jooß, K. AU - Hühner, J.* AU - Kiessig, S.* AU - Moritz, B.* AU - Neusüß, C.* C1 - 51737 C2 - 43426 CY - Heidelberg SP - 6057–6067 TI - Two-dimensional capillary zone electrophoresis–mass spectrometry for the characterization of intact monoclonal antibody charge variants, including deamidation products. JO - Anal. Bioanal. Chem. VL - 409 IS - 26 PB - Springer Heidelberg PY - 2017 SN - 1618-2642 ER - TY - JOUR AB - Metabolite profiling of urine has seen much advancement in recent years, and its analysis by nuclear magnetic resonance (NMR) spectroscopy has become well established. However, the highly variable nature of human urine still requires improved protocols despite some standardization. In particular, diseases such as kidney disease can have a profound effect on the composition of urine and generate a highly diverse sample set for clinical studies. Large variations in pH and the cationic concentration of urine play an important role in creating positional noise within datasets generated from NMR. We demonstrate positional noise to be a confounding variable for multivariate statistical tools such as statistical total correlation spectroscopy (STOCSY), thereby hindering the process of biomarker discovery. We present a two-dimensional buffering system using potassium fluoride (KF) and phosphate buffer to reduce positional noise in metabolomic data generated from urine samples with various levels of proteinuria. KF reduces positional noise in citrate peaks, by decreasing the mean relative standard deviation (RSD) from 0.17 to 0.09. By reducing positional noise with KF, STOCSY analysis of citrate peaks saw significant improvement. We further aligned spectral data using a recursive segment-wise peak alignment (RSPA) method, which leads to further improvement of the positional noise (RSD = 0.06). These results were validated using diverse selection of metabolites which lead to an overall improvement in positional noise using the suggested protocol. In summary, we provide an improved workflow for urine metabolite biomarker discovery to achieve higher data quality for better pathophysiological understanding of human diseases. Graphical abstract Citrate peaks in the range 2.75-2.5 ppm from datasets with different sample preparation protocols and with/without in silico alignment. A Citrate peaks with standard phosphate buffering and without in silico alignment. B citrate peaks with standard phosphate buffering and with in silico alignment. C citrate peak with additional potassium fluoride and standard phosphate buffering without in silico alignment. D citrate peaks with additional potassium fluoride and standard phosphate buffering with in silico alignment. Below the respective spectrum are displayed the percent relative standard deviation (RSD) of the respective citrate peaks. This is a measure of the positional noise of peaks within a (1)H NMR analysis. It can be seen that D performs the best in reducing positional noise of citrate peaks. E-H STOCSY analysis of correlating spectral features with the driver peak at 2.675 ppm (see red arrow) to identify structural correlations. As a, b, c, and d are known to be structurally correlated, STOCSY analysis should reveal r (2) = 1 if data is perfectly aligned and can therefore be used as a measure of peak alignment. E Strong positional noise does not allow identifying the c and d peaks of the AB system to be correlated. F, G Neither in silico alignment or KF addition alone can completely improve the alignment and therefore increase the correlations. H Highly improved alignment by combining both KF addition and in silico alignment reduces positional noise and elucidates all four citrate peaks to be strongly correlated. AU - Gil, R.B. AU - Lehmann, R. AU - Schmitt-Kopplin, P. AU - Heinzmann, S.S. C1 - 48600 C2 - 41199 CY - Heidelberg SP - 4683-4691 TI - 1H NMR-based metabolite profiling workflow to reduce inter-sample chemical shift variations in urine samples for improved biomarker discovery. JO - Anal. Bioanal. Chem. VL - 408 IS - 17 PB - Springer Heidelberg PY - 2016 SN - 1618-2642 ER - TY - JOUR AB - Molecular formula assignment is one of the key challenges in processing high-field Fourier transform ion cyclotron resonance mass spectrometric (FT-ICR-MS) datasets. The number of potential solutions for an elemental formula increases exponentially with increasing molecular mass, especially when non-oxygen heteroatoms like N, S or P are included. A method was developed from the chemical perspective and validated using a Suwannee River Fulvic Acid (SRFA) dataset which is dominated by components consisting exclusively of C, H and O (78 % CHO). In order to get information on the application range and robustness of this method, we investigated a FT-ICR-MS dataset which was merged from 18 mine pit lake pore waters and 3 river floodplain soil waters. This dataset contained 50 % CHO and 18 % CHOS on average, whereas the former SRFA dataset contained only 1.5 % CHOS. The mass calculator was configured to allow up to five nitrogen atoms and up to one sulphur atom in assigning formulas to mass peaks. More than 50 % multiple-formula assignments were found for peaks with masses > 650 Da. Based on DBE - O frequency diagrams, many CHO, CHOS1, CHON1 and CHON1S1 molecular series were ultimately assigned to many m/z and considered to be reliable solutions. The unequivocal data pool could thus be enlarged by 523 (6.8 %) CHOS1 components. In contrast to the method validation with CHO-rich SRFA, validation with sulphur-rich pit lake samples showed that formulas with a higher number of non-oxygen heteroatoms can be more reliable assignments in many cases. As an example: CHOS molecular series were reliable and the CHO classes were unreliable amongst other molecular classes in many multiple-formula assignments from the sulphur-rich pit lake samples. Graphical abstract An exemplary frequency versus DBE - O diagram. CHOS components but not CHO (and not CHON2 or CHON2S) components were considered here reliable. AU - Herzsprung, P.* AU - Hertkorn, N. AU - von Tümpling, W.* AU - Harir, M. AU - Friese, K.* AU - Schmitt-Kopplin, P. C1 - 47909 C2 - 39754 CY - Heidelberg SP - 2461-2469 TI - Molecular formula assignment for Dissolved Organic Matter (DOM) using high-field FT-ICR-MS: Chemical perspective and validation of sulphur-rich organic components (CHOS) in pit lake samples. JO - Anal. Bioanal. Chem. VL - 408 IS - 10 PB - Springer Heidelberg PY - 2016 SN - 1618-2642 ER - TY - JOUR AB - Tissue distribution and quantitative analysis of small molecules is a key to assess the mechanism of drug action and evaluate treatment efficacy. The prodrug irinotecan (CPT-11) is widely used for chemotherapeutic treatment of colorectal cancer. CPT-11 requires conversion into its active metabolite SN-38 to exert the desired pharmacological effect. MALDI-Fourier transform ion cyclotron resonance (FT-ICR) and MALDI-time-of-flight (TOF) mass spectrometry imaging (MSI) were performed for detection of CPT-11 and SN-38 in tissue sections from mice post CPT-11 injection. In-depth information was gained about the distribution and quantity of drug compounds in normal and tumor tissue. The prodrug was metabolized, as proven by the detection of SN-38 in liver, kidney and digestive tract. In tumors from genetic mouse models for colorectal cancer (Apc (1638N/wt) x pvillin-Kras (V12G) ), CPT-11 was detected but not the active metabolite. In order to correlate drug distribution relative to vascularization, MALDI data were superimposed with CD31 (PECAM-1) immunohistochemistry. This analysis indicated that intratumoral access of CPT-11 mainly occurred by extravasation from microvessels. The present study exploits the power of MALDI MSI in drug analysis, and presents a novel approach to monitor drug distribution in relation to vessel functionality in preclinical and clinical research. AU - Buck, A. AU - Halbritter, S. AU - Späth, C.* AU - Feuchtinger, A. AU - Aichler, M. AU - Zitzelsberger, H. AU - Janssen, K.P.* AU - Walch, A.K. C1 - 32556 C2 - 35132 CY - Heidelberg SP - 2107-2116 TI - Distribution and quantification of irinotecan and its active metabolite SN-38 in colon cancer murine model systems using MALDI MSI. JO - Anal. Bioanal. Chem. VL - 407 IS - 8 PB - Springer Heidelberg PY - 2015 SN - 1618-2642 ER - TY - JOUR AB - The time- and space-resolved chemical signatures of gases and vapours formed in solid-state combustion processes are difficult to examine using recent analytical techniques. A machine-smoked cigarette represents a very reproducible model system for dynamic solid-state combustion. By using a special sampling system (microprobe unit) that extracts the formed gases from inside of the burning cigarette, which is coupled to a photoionisation mass spectrometer, it was possible to study the evolution of organic gases during a 2-s cigarette puff. The concentrations of various pyrolysis and combustion products such as 1,3-butadiene, toluene, acetaldehyde and phenol were monitored on-line at different sampling points within cigarettes. A near-microscopic-scale spatial resolution and a 200-ms time resolution were achieved. Finally, the recorded information was combined to generate time-resolved concentration maps, showing the formation and destruction zones of the investigated compounds in the burning cigarette. The combustion zone at the tip of cigarette, where e.g. 1,3-butadiene is predominately formed, was clearly separable from the pyrolysis zones. Depending on the stability of the precursor (e.g. lignin or cellulose), the position of pyrolytic formation varies. In conclusion, it was demonstrated that soft photoionisation mass spectrometry in conjunction with a microprobe sampling device can be used for time- and space-resolved analysis of combustion and pyrolysis reactions. In addition to studies on the model cigarette, further model systems may be studied with this approach. This may include further studies on the combustion of biomass or coal chunks, on heterogeneously catalysed reactions or on spray, dust and gas combustion processes. AU - Hertz-Schünemann, R. AU - Ehlert, S. AU - Streibel, T. AU - Liu, C.* AU - McAdam, K.* AU - Baker, R.R.* AU - Zimmermann, R. C1 - 43190 C2 - 36309 CY - Heidelberg SP - 2293-2299 TI - High-resolution time and spatial imaging of tobacco and its pyrolysis products during a cigarette puff by microprobe sampling photoionisation mass spectrometry. JO - Anal. Bioanal. Chem. VL - 407 IS - 8 PB - Springer Heidelberg PY - 2015 SN - 1618-2642 ER - TY - JOUR AB - Ship diesel combustion particles are known to cause broad cytotoxic effects and thereby strongly impact human health. Particles from heavy fuel oil (HFO) operated ships are considered as particularly dangerous. However, little is known about the relevant components of the ship emission particles. In particular, it is interesting to know if the particle cores, consisting of soot and metal oxides, or the adsorbate layers, consisting of semi- and low-volatile organic compounds and salts, are more relevant. We therefore sought to relate the adsorbates and the core composition of HFO combustion particles to the early cellular responses, allowing for the development of measures that counteract their detrimental effects. Hence, the semi-volatile coating of HFO-operated ship diesel engine particles was removed by stepwise thermal stripping using different temperatures. RAW 264.7 macrophages were exposed to native and thermally stripped particles in submersed culture. Proteomic changes were monitored by two different quantitative mass spectrometry approaches, stable isotope labeling by amino acids in cell culture (SILAC) and dimethyl labeling. Our data revealed that cells reacted differently to native or stripped HFO combustion particles. Cells exposed to thermally stripped particles showed a very differential reaction with respect to the composition of the individual chemical load of the particle. The cellular reactions of the HFO particles included reaction to oxidative stress, reorganization of the cytoskeleton and changes in endocytosis. Cells exposed to the 280 °C treated particles showed an induction of RNA-related processes, a number of mitochondria-associated processes as well as DNA damage response, while the exposure to 580 °C treated HFO particles mainly induced the regulation of intracellular transport. In summary, our analysis based on a highly reproducible automated proteomic sample-preparation procedure shows a diverse cellular response, depending on the soot particle composition. In particular, it was shown that both the molecules of the adsorbate layer as well as particle cores induced strong but different effects in the exposed cells. AU - Kanashova, T.* AU - Popp, O.* AU - Orasche, J. AU - Karg, E.W.* AU - Harndorf, H.* AU - Stengel, B.* AU - Sklorz, M.* AU - Streibel, T.* AU - Zimmermann, R. AU - Dittmar, G.A.G.* C1 - 43863 C2 - 36757 CY - Heidelberg SP - 5965-5976 TI - Differential proteomic analysis of mouse macrophages exposed to adsorbate-loaded heavy fuel oil derived combustion particles using an automated sample-preparation workflow. JO - Anal. Bioanal. Chem. VL - 407 IS - 20 PB - Springer Heidelberg PY - 2015 SN - 1618-2642 ER - TY - JOUR AB - Insulin resistance (IR) lies at the origin of type 2 diabetes. It induces initial compensatory insulin secretion until insulin exhaustion and subsequent excessive levels of glucose (hyperglycemia). A high-calorie diet is a major risk factor contributing to the development of this metabolic disease. For this study, a time-course experiment was designed that consisted of two groups of mice. The aim of this design was to reproduce the dietary conditions that parallel the progress of IR over time. The first group was fed with a high-fatty-acid diet for several weeks and followed by 1 week of a low-fatty-acid intake, while the second group was fed with a low-fatty-acid diet during the entire experiment. The metabolomic fingerprint of C3HeB/FeJ mice liver tissue extracts was determined by means of two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-ToF-MS). This article addresses the application of ANOVA-simultaneous component analysis (ASCA) to the found metabolomic profile. By performing hyphenated high-throughput analytical techniques together with multivariate chemometric methodology on metabolomic analysis, it enables us to investigate the sources of variability in the data related to each experimental factor of the study design (defined as time, diet and individual). The contribution of the diet factor in the dissimilarities between the samples appeared to be predominant over the time factor contribution. Nevertheless, there is a significant contribution of the time-diet interaction factor. Thus, evaluating the influences of the factors separately, as it is done in classical statistical methods, may lead to inaccurate interpretation of the data, preventing achievement of consistent biological conclusions. AU - Ly-Verdú, S. AU - Gröger, T.M. AU - Arteaga-Salas, J.M. AU - Brandmaier, S. AU - Kahle-Stephan, M. AU - Neschen, S. AU - Hrabě de Angelis, M. AU - Zimmermann, R. C1 - 42869 C2 - 35649 SP - 343-354 TI - Combining metabolomic non-targeted GC×GC-ToF-MS analysis and chemometric ASCA-based study of variances to assess dietary influence on type 2 diabetes development in a mouse model. JO - Anal. Bioanal. Chem. VL - 407 IS - 1 PY - 2015 SN - 1618-2642 ER - TY - JOUR AU - McDonnell, L.A.* AU - Römpp, A.* AU - Balluff, B.D.* AU - Heeren, R.M.A.* AU - Albar, J.P.* AU - Andrén, P.E.* AU - Corthals, G.L.* AU - Walch, A.K. AU - Stoeckli, M.* C1 - 42918 C2 - 35864 CY - Heidelberg SP - 2035-2045 TI - Discussion point: Reporting guidelines for mass spectrometry imaging. JO - Anal. Bioanal. Chem. VL - 407 IS - 8 PB - Springer Heidelberg PY - 2015 SN - 1618-2642 ER - TY - JOUR AB - To assess sources and degradation of the herbicide glyphosate [N-(phosphonomethyl) glycine] and its metabolite AMPA (aminomethylphosphonic acid), concentration measurements are often inconclusive and even (13)C/(12)C analysis alone may give limited information. To advance isotope ratio analysis of an additional element, we present compound-specific (15)N/(14)N analysis of glyphosate and AMPA by a two step derivatization in combination with gas chromatography/isotope ratio mass spectrometry (GC/IRMS). The N-H group was derivatized with isopropyl chloroformate (iso-PCF), and remaining acidic groups were subsequently methylated with trimethylsilyldiazomethane (TMSD). Iso-PCF treatment at pH <10 gave too low (15)N/(14)N ratios indicating an incomplete derivatization; in contrast, too high (15)N/(14)N ratios at pH >10 indicated decomposition of the derivative. At pH 10, and with an excess of iso-PCF by 10-24, greatest yields and accurate (15)N/(14)N ratios were obtained (deviation from elemental analyzer-IRMS: -0.2 ± 0.9 % for glyphosate; -0.4 ± 0.7 % for AMPA). Limits for accurate δ(15)N analysis of glyphosate and AMPA were 150 and 250 ng injected, respectively. A combination of δ(15)N and δ(13)C analysis by liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) (1) enabled an improved distinction of commercial glyphosate products and (2) showed that glyphosate isotope values during degradation by MnO2 clearly fell outside the commercial product range. This highlights the potential of combined carbon and nitrogen isotopes analysis to trace sources and degradation of glyphosate. AU - Mogusu, E.O. AU - Wolbert, J.B.* AU - Kujawinski, D.M.* AU - Jochmann, M.A.* AU - Elsner, M. C1 - 44869 C2 - 37178 CY - Heidelberg SP - 5249-5260 TI - Dual element (15N/ 14N, 13C/ 12C) isotope analysis of glyphosate and AMPA by derivatization-gas chromatography isotope ratio mass spectrometry (GC/IRMS) combined with LC/IRMS. JO - Anal. Bioanal. Chem. VL - 407 IS - 18 PB - Springer Heidelberg PY - 2015 SN - 1618-2642 ER - TY - JOUR AB - In this study, we produced a class of diffusion flame soot particles with varying chemical and physical properties by using the mini-Combustion Aerosol STandard (CAST) and applying varying oxidant gas flow rates under constant propane, quenching, and dilution gas supply. We varied the soot properties by using the following fuel-to-air equivalence ratios (Φ): 1.13, 1.09, 1.04, 1.00, 0.96, and 0.89. Within this Φ range, we observed drastic changes in the physical and chemical properties of the soot. Oxidant-rich flames (Φ < 1) were characterized by larger particle size, lower particle number concentration, higher black carbon (BC) concentration, lower brown carbon BrC.[BC](-1) than fuel-rich flames (Φ > 1). To investigate the polycyclic aromatic hydrocarbons (PAH) formation online, we developed a new method for quantification by using the one (13)C-containing doubly charged PAH ion in a high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS). The time-resolved concentration showed that the larger PAHs prevailed in the fuel-rich flames and diminished in the oxidant-rich flames. By comparison with the offline in situ derivatization-thermal-desorption gas-chromatography time-of-flight mass spectrometry (IDTD-GC-ToF-MS), we found that the concentration by using the HR-ToF-AMS was underestimated, especially for lower mass PAHs (C14-C18) in the fuel-rich flames possibly due to size limitation and degradation of semi-volatile species under high vacuum and desorption temperature in the latter. For oxidant-rich flames, the large PAHs (C20 and C22) were detected in the HR-ToF-AMS while it was not possible in IDTD-GC-ToF-MS due to matrix effect. The PAH formation was discussed based on the combination of our results and with respect to Φ settings. AU - Müller, L. AU - Jakobi, G. AU - Orasche, J. AU - Karg, E.W. AU - Sklorz, M.* AU - Abbaszade, G. AU - Weggler, B.A. AU - Jing, L.* AU - Schnelle-Kreis, J. AU - Zimmermann, R. C1 - 43515 C2 - 36654 CY - Heidelberg SP - 5911-5922 TI - Online determination of polycyclic aromatic hydrocarbon formation from a flame soot generator. JO - Anal. Bioanal. Chem. VL - 407 IS - 20 PB - Springer Heidelberg PY - 2015 SN - 1618-2642 ER - TY - JOUR AB - The publisher regrets that due to a conversion problem there were mistakes in this article. [13C12C2þ ] The following equations should correctly read:n−1 yHR−TOF−AMS ¼ ½PAH]HR−TOF−AMS 12C2þ TICn ¼ r ð1Þ12C2þx0:011 x n ¼ P ð2Þ Our sincere apologies to the authors. n. AU - Müller, L. AU - Jakobi, G. AU - Orasche, J. AU - Karg, E.W. AU - Sklorz, M.* AU - Abbaszade, G. AU - Weggler, B.A. AU - Jing, L.* AU - Schnelle-Kreis, J. AU - Zimmermann, R. C1 - 43977 C2 - 39450 CY - Heidelberg TI - Erratum to: Online determination of polycyclic aromatic hydrocarbon formation from a flame soot generator (Anal Bioanal Chem), 10.1007/s00216-015-8549-x. JO - Anal. Bioanal. Chem. VL - 407 IS - 20 PB - Springer Heidelberg PY - 2015 SN - 1618-2642 ER - TY - JOUR AB - Organic combustion aerosols from a marine medium-speed diesel engine, capable to run on distillate (diesel fuel) and residual fuels (heavy fuel oil), were investigated under various operating conditions and engine parameters. The online chemical characterisation of the organic components was conducted using a resonance-enhanced multiphoton ionisation time-of-flight mass spectrometer (REMPI TOF MS) and a proton transfer reaction-quadrupole mass spectrometer (PTR-QMS). Oxygenated species, alkenes and aromatic hydrocarbons were characterised. Especially the aromatic hydrocarbons and their alkylated derivatives were very prominent in the exhaust of both fuels. Emission factors of known health-hazardous compounds (e.g. mono- and poly-aromatic hydrocarbons) were calculated and found in higher amounts for heavy fuel oil (HFO) at typical engine loadings. Lower engine loads lead in general to increasing emissions for both fuels for almost every compound, e.g. naphthalene emissions varied for diesel fuel exhaust between 0.7 mg/kWh (75 % engine load, late start of injection (SOI)) and 11.8 mg/kWh (10 % engine load, late SOI) and for HFO exhaust between 3.3 and 60.5 mg/kWh, respectively. Both used mass spectrometric techniques showed that they are particularly suitable methods for online monitoring of combustion compounds and very helpful for the characterisation of health-relevant substances. AU - Radischat, C.* AU - Sippula, O.* AU - Stengel, B.* AU - Klingbeil, S.* AU - Sklorz, M. AU - Rabe, R.* AU - Streibel, T. AU - Harndorf, H.* AU - Zimmermann, R. C1 - 43286 C2 - 36339 CY - Heidelberg SP - 5939-5951 TI - Real-time analysis of organic compounds in ship engine aerosol emissions using resonance-enhanced multiphoton ionisation and proton transfer mass spectrometry. JO - Anal. Bioanal. Chem. VL - 407 IS - 20 PB - Springer Heidelberg PY - 2015 SN - 1618-2642 ER - TY - JOUR AB - In this study, positive-mode laser desorption-ionisation ultra-high-resolution mass spectrometry (LDI-FT-ICR-MS) was applied to study combustion aerosol samples obtained from a ship diesel engine as well as the feed fuel, used to operate the engine. Furthermore, particulate matter was sampled from the exhaust tube using an impactor and analysed directly from the impaction foil without sample treatment. From the high percentage of shared sum formula as well as similarities in the chemical spread of aerosol and heavy fuel oil, results indicate that the primary aerosol mainly consists of survived, unburned species from the feed fuel. The effect of pyrosynthesis could be observed and was slightly more pronounced for the CH-class compared to other compound classes, but in summary not dominant. Alkylation pattern as well as the aromaticity distribution, using the double bond equivalent, revealed a shift towards lower alkylation state for the aerosol. The alkylation pattern of the most dominant series revealed a higher correlation between different aerosol samples than between aerosol and feed samples. This was confirmed by cluster analysis. Overall, this study shows that LDI-FT-ICR-MS can be successfully applied for the analysis of combustion aerosol at the molecular level and that sum formula information can be used to identify chemical differences between aerosol and fuel as well as between different size fractions of the particulate matter. AU - Rüger, C.P.* AU - Sklorz, M. AU - Schwemer, T.* AU - Zimmermann, R. C1 - 43284 C2 - 36338 CY - Heidelberg SP - 5923-5937 TI - Characterisation of ship diesel primary particulate matter at the molecular level by means of ultra-high-resolution mass spectrometry coupled to laser desorption ionisation - comparison of feed fuel, filter extracts and direct particle measurements. JO - Anal. Bioanal. Chem. VL - 407 IS - 20 PB - Springer Heidelberg PY - 2015 SN - 1618-2642 ER - TY - JOUR AB - In metabolomics there is an ever-growing need for faster and more comprehensive analysis methods to cope with the increasing size of biological studies. Direct-infusion ion-cyclotron-resonance Fourier-transform spectrometry (DI-ICR-FT-MS) is used in non-targeted metabolomics to obtain high-resolution snapshots of the metabolic state of a system. We applied this technology to a Caenorhabditis elegans-Pseudomonas aeruginosa infection model and optimized times needed for cultivation and mass-spectrometric analysis. Our results reveal that DI-ICR-FT-MS is a promising tool for high-throughput in-depth non-targeted metabolomics. We performed whole-worm metabolomics and recovered markers of the induced metabolic changes in C. elegans brought about by interaction with pathogens. In this investigation, we reveal complex metabolic phenotypes enabling clustering based upon challenge. Specifically, we observed a marked decrease in amino-acid metabolism with infection by P. aeruginosa and a marked increase in sugar metabolism with infection by Salmonella enterica. We were also able to discriminate between infection with a virulent wild-type Pseudomonas and with an attenuated mutant, making it possible to use this method in larger genetic screens to identify host and pathogen effectors affecting the metabolic phenotype of infection. AU - Witting, M. AU - Lucio, M. AU - Tziotis, D. AU - Wägele, B. AU - Suhre, K. AU - Voulhoux, R.* AU - Garvis, S.* AU - Schmitt-Kopplin, P. C1 - 42852 C2 - 35816 CY - Heidelberg SP - 1059-1073 TI - DI-ICR-FT-MS-based high-throughput deep metabotyping: A case study of the Caenorhabditis elegans-Pseudomonas aeruginosa infection model. JO - Anal. Bioanal. Chem. VL - 407 IS - 4 PB - Springer Heidelberg PY - 2015 SN - 1618-2642 ER - TY - JOUR AB - Every day, analytical and bio-analytical chemists make sustained efforts to improve the sensitivity, specificity, robustness, and reproducibility of their methods. Especially in targeted and non-targeted profiling approaches, including metabolomics analysis, these objectives are not easy to achieve; however, robust and reproducible measurements and low coefficients of variation (CV) are crucial for successful metabolomics approaches. Nevertheless, all efforts from the analysts are in vain if the sample quality is poor, i.e. if preanalytical errors are made by the partner during sample collection. Preanalytical risks and errors are more common than expected, even when standard operating procedures (SOP) are used. This risk is particularly high in clinical studies, and poor sample quality may heavily bias the CV of the final analytical results, leading to disappointing outcomes of the study and consequently, although unjustified, to critical questions about the analytical performance of the approach from the partner who provided the samples. This review focuses on the preanalytical phase of liquid chromatography-mass spectrometry-driven metabolomics analysis of body fluids. Several important preanalytical factors that may seriously affect the profile of the investigated metabolome in body fluids, including factors before sample collection, blood drawing, subsequent handling of the whole blood (transportation), processing of plasma and serum, and inadequate conditions for sample storage, will be discussed. In addition, a detailed description of latent effects on the stability of the blood metabolome and a suggestion for a practical procedure to circumvent risks in the preanalytical phase will be given. AU - Yin, P.* AU - Lehmann, R. AU - Xu, G.* C1 - 46295 C2 - 37497 CY - Heidelberg SP - 4879-4892 TI - Effects of pre-analytical processes on blood samples used in metabolomics studies. JO - Anal. Bioanal. Chem. VL - 407 IS - 17 PB - Springer Heidelberg PY - 2015 SN - 1618-2642 ER - TY - JOUR AU - Zimmermann, R. C1 - 46324 C2 - 37593 CY - Heidelberg SP - 5863-5867 TI - Aerosols and health: A challenge for chemical and biological analysis. JO - Anal. Bioanal. Chem. VL - 407 IS - 20 PB - Springer Heidelberg PY - 2015 SN - 1618-2642 ER - TY - JOUR AB - In this interdisciplinary approach, the dynamics of production and degradation of the quorum sensing signal 3-oxo-decanoylhomoserine lactone were studied for continuous cultures of Pseudomonas putida IsoF. The signal concentrations were quantified over time by use of monoclonal antibodies and ELISA. The results were verified by use of ultra-high-performance liquid chromatography. By use of a mathematical model we derived quantitative values for non-induced and induced signal production rate per cell. It is worthy of note that we found rather constant values for different rates of dilution in the chemostat, and the values seemed close to those reported for batch cultures. Thus, the quorum-sensing system in P. putida IsoF is remarkably stable under different environmental conditions. In all chemostat experiments, the signal concentration decreased strongly after a peak, because emerging lactonase activity led to a lower concentration under steady-state conditions. This lactonase activity probably is quorum sensing-regulated. The potential ecological implication of such unique regulation is discussed. AU - Buddrus-Schiemann, K.* AU - Rieger, M. AU - Mühlbauer, M.* AU - Barbarossa, M.V.* AU - Kuttler, C. AU - Hense, B.A. AU - Rothballer, M. AU - Uhl, J.* AU - Fonseca, J.R.* AU - Schmitt-Kopplin, P. AU - Schmid, M. AU - Hartmann, A. C1 - 31874 C2 - 34900 CY - Heidelberg SP - 6373-6383 TI - Analysis of N-acylhomoserine lactone dynamics in continuous cultures of Pseudomonas putida IsoF by use of ELISA and UHPLC/qTOF-MS-derived measurements and mathematical models. JO - Anal. Bioanal. Chem. VL - 406 IS - 25 PB - Springer Heidelberg PY - 2014 SN - 1618-2642 ER - TY - JOUR AB - Formula assignment is one of the key challenges in evaluation of dissolved organic matter analyses using ultrahigh resolution mass spectrometry (FTICR MS). The number of possible solutions for elemental formulas grows exponentially with increasing nominal mass, especially when non-oxygen heteroatoms like N, S or P are considered. Until now, no definitive solution for finding the correct elemental formula has been given. For that reason an approach from the viewpoint of chemical feasibility was elucidated. To illustrate the new chemical formula assignment principle, a literature data set was used and evaluated by simplified chemical constraints. Only formulas containing a maximum of one sulphur and five nitrogen atoms were selected for further data processing. The resulting data table was then divided into mass peaks with unique component solutions (singlets, representing unequivocal formula assignments) and those with two or more solutions (multiple formula assignments, representing equivocal formula assignments). Based on a [double bond equivalent (DBE) versus the number of oxygen atoms (o)] frequency contour plot and a frequency versus [DBE minus o] diagram, a new assessment and decision strategy was developed to differentiate multiple formula assignments into chemically reliable and less reliable molecular formulas. Using this approach a considerable number of reliable components were identified within the equivocal part of the data set. As a control, a considerable proportion of the assigned formulas deemed to be reliable correspond to those which would have been obtained by CH 2 -based Kendrick mass defect analysis. We conclude that formula assignment in complex mixtures can be improved by group-wise decisions based on the frequency and the [DBE minus o] values of multiple formula assignments. AU - Herzsprung, P.* AU - Hertkorn, N. AU - von Tümpling, W.* AU - Harir, M. AU - Friese, K.* AU - Schmitt-Kopplin, P. C1 - 32660 C2 - 35202 SP - 7977-7987 TI - Understanding molecular formula assignment of Fourier transform ion cyclotron resonance mass spectrometry data of natural organic matter from a chemical point of view. JO - Anal. Bioanal. Chem. VL - 406 IS - 30 PY - 2014 SN - 1618-2642 ER - TY - JOUR AB - In human medicine, procalcitonin (PCT) is a very common and well-established biomarker for sepsis. Even though sepsis is also a leading cause of death in foals and adult horses, up to now, no data about the role of equine PCT in septic horses has been available. Based on monoclonal antibodies targeted against human PCT, we report here the development of a sandwich ELISA for the quantification of equine PCT in equine plasma samples. The ELISA was characterized for intra- and interassay variance and a working range from 25 to 1,000 ng mL(-1) was defined as within this range; both intra- and interassay variances were below 15 %. The target recovery ranged between 73 and 106 %. The ELISA was used to determine the equine PCT concentration in 24 healthy and 5 septic horses to show the potential for clinical evaluation of equine PCT. Significantly different (P = 0.0006) mean equine PCT concentrations were found for the healthy control group and the sepsis group (47 and 8,450 ng mL(-1)). AU - Rieger, M. AU - Kochleus, C. AU - Teschner, D.* AU - Rascher, D. AU - Barton, A.K.* AU - Geerlof, A. AU - Kremmer, E. AU - Schmid, M. AU - Hartmann, A. AU - Gehlen, H.* C1 - 31618 C2 - 34628 CY - Heidelberg SP - 5507-5512 TI - A new ELISA for the quantification of equine procalcitonin in plasma as potential inflammation biomarker in horses. JO - Anal. Bioanal. Chem. VL - 406 IS - 22 PB - Springer PY - 2014 SN - 1618-2642 ER - TY - JOUR AB - Gram-negative bacteria use N-acylhomoserine lactones (AHLs) as their command language to coordinate population behavior during invasion and colonization of higher organisms. Although many different bacterial bioreporters are available for AHLs monitoring, in which a phenotypic response, e.g. bioluminescence, violacin production, and β-galactosidase activity, is exploited, mass spectrometry (MS) is the most versatile detector for rapid analysis of AHLs in complex microbial samples, with or without prior separation steps. In this paper we critically review recent advances in the application of high-resolution MS to analysis of the quorum sensing (QS) signaling molecules used by Gram-negative bacteria, with much emphasis on AHLs. A critical review of the use of bioreporters in the study of AHLs is followed by a short methodological survey of the capabilities of high-resolution mass spectrometry (HRMS), including Fourier-transform ion cyclotron resonance (FTICR) MS and quadrupole time-of-flight (qTOF) MS. Use of infusion electrospray ultrahigh-resolution FTICR MS (12 Tesla) enables accurate mass measurements for determination of the elemental formulas of AHLs in Acidovorax sp. N35 and Burkholderia ubonensis AB030584. Results obtained by coupling liquid chromatography with a hybrid quadrupole linear ion trap-FTICR mass spectrometer (LC-LTQ-FTICRMS, 7-T) for characterization of acylated homoserine lactones in the human pathogen Pseudomonas aeruginosa are presented. UPLC-ESI-qTOF MS has also proved to be suitable for identification of 3O-C(10)HSL in Pseudomonas putida IsoF cell culture supernatant. Aspects of sample preparation and the avoidance of analytical pitfalls are also emphasized. AU - Cataldi, T.R.I.* AU - Bianco, G.* AU - Fonseca, J. AU - Schmitt-Kopplin, P. C1 - 22555 C2 - 30911 SP - 493-507 TI - Perceiving the chemical language of gram-negative bacteria: Listening by high-resolution mass spectrometry. JO - Anal. Bioanal. Chem. VL - 405 IS - 2-3 PB - Springer PY - 2013 SN - 1618-2642 ER - TY - JOUR AB - Considering current security issues, powerful tools for detection of security-relevant substances such as traces of explosives and drugs/drug precursors related to clandestine laboratories are required. Especially in the field of detection of explosives and improvised explosive devices, several relevant compounds exhibit a very low vapor pressure. Ambient pressure laser desorption is proposed to make these substances available in the gas phase for the detection by adapted mass spectrometers or in the future with ion-mobility spectrometry as well. In contrast to the state-of-the-art thermal desorption approach, by which the sample surface is probed for explosive traces by a wipe pad being transferred to a thermal desorber unit, by the ambient pressure laser desorption approach presented here, the sample is directly shockwave ablated from the surface. The laser-dispersed molecules are sampled by a heated sniffing capillary located in the vicinity of the ablation spot into the mass analyzer. This approach has the advantage that the target molecules are dispersed more gently than in a thermal desorber unit where the analyte molecules may be decomposed by the thermal intake. In the technical realization, the sampling capillary as well as the laser desorption optics are integrated in the tip of an endoscopic probe or a handheld sampling module. Laboratory as well as field test scenarios were performed, partially in cooperation with the Federal Criminal Police Office (Bundeskriminalamt, BKA, Wiesbaden, Germany), in order to demonstrate the applicability for various explosives, drugs, and drug precursors. In this work, we concentrate on the detection of explosives. A wide range of samples and matrices have been investigated successfully. AU - Ehlert, S.* AU - Hölzer, J. AU - Rittgen, J.* AU - Pütz, M.* AU - Schulte-Ladbeck, R.* AU - Zimmermann, R. C1 - 26128 C2 - 32083 SP - 6979-6993 TI - Rapid on-site detection of explosives on surfaces by ambient pressure laser desorption and direct inlet single photon ionization or chemical ionization mass spectrometry. JO - Anal. Bioanal. Chem. VL - 405 IS - 22 PB - Springer PY - 2013 SN - 1618-2642 ER - TY - JOUR AB - A micro-probe (μ-probe) gas sampling device for on-line analysis of gases evolving in confined, small objects by single-photon ionisation time-of-flight mass spectrometry (SPI-TOFMS) was developed. The technique is applied for the first time in a feasibility study to record the formation of volatile and flavour compounds during the roasting process within (inside) or in the direct vicinity (outside) of individual coffee beans. A real-time on-line analysis of evolving volatile and semi-volatile organic compounds (VOC and SVOC) as they are formed under the mild pyrolytic conditions of the roasting process was performed. The soft-ionisation mass spectra depict a molecular ion signature, which is well corresponding with the existing knowledge of coffee roasting and evolving compounds. Additionally, thereby it is possible to discriminate between Coffea arabica (Arabica) and Coffea canephora (Robusta). The recognized differences in the roasting gas profiles reflect the differences in the precursor composition of the coffee cultivars very well. Furthermore, a well-known set of marker compounds for Arabica and Robusta, namely the lipids kahweol and cafestol (detected in their dehydrated form at m/z 296 and m/z 298, respectively) were observed. If the variation in time of different compounds is observed, distinctly different evolution behaviours were detected. Here, phenol (m/z 94) and caffeine (m/z 194) are exemplary chosen, whereas phenol shows very sharp emission peaks, caffeine do not have this highly transient behaviour. Finally, the changes of the chemical signature as a function of the roasting time, the influence of sampling position (inside, outside) and cultivar (Arabica, Robusta) is investigated by multivariate statistics (PCA). In summary, this pilot study demonstrates the high potential of the measurement technique to enhance the fundamental knowledge of the formation processes of volatile and semi-volatile flavour compounds inside the individual coffee bean. AU - Hertz-Schünemann, R.* AU - Streibel, T. AU - Ehlert, S.* AU - Zimmermann, R. C1 - 26156 C2 - 32097 SP - 7083-7096 TI - Looking into individual coffee beans during the roasting process: Direct micro-probe sampling on-line photo-ionisation mass spectrometric analysis of coffee roasting gases. JO - Anal. Bioanal. Chem. VL - 405 IS - 22 PB - Springer PY - 2013 SN - 1618-2642 ER - TY - JOUR AB - In the wake of genomics, metabolomics characterizes the small molecular metabolites revealing the phenotypes induced by gene mutants. To address the metabolic signatures in the hippocampus of the amyloid-beta (Aβ) peptides produced in transgenic (Tg) CRND8 mice, high-field ion cyclotron resonance-Fourier transform mass spectrometry supported by LC-LTQ-Orbitrap was introduced to profile the extracted metabolites. More than 10,000 ions were detected in the mass profile for each sample. Subsequently, peak alignment and the 80 % rule followed by feature selection based on T score computation were performed. The putative identification was also conducted using the highly accurate masses with isotopic distribution by interfacing the MassTRIX database as well as MS/MS fragmentation generated in the LTQ-Orbitrap after chromatographic separation. Consequently, 58 differentiating masses were tentatively identified while up to 44 differentiating elemental compositions could not be biologically annotated in the databases. Nonetheless, of the putatively annotated masses, eicosanoids in arachidonic acid metabolism, fatty acid beta-oxidation disorders as well as disturbed glucose metabolism were highlighted as metabolic traits of Aβ toxicity in Tg CRND8 mice. Furthermore, a web-based bioinformatic tool was used for simulation of the metabolic pathways. As a result of the obtained metabolic signatures, the arachidonic acid metabolism dominates the metabolic perturbation in hippocampal tissues of Tg CRND8 mice compared to non-Tg littermates, indicating that Aβ toxicity functions neuroinflammation in hippocampal tissue and new theranostic opportunities might be offered by characterization of altered arachidonic acid metabolism for Alzheimer's disease. AU - Lin, S.* AU - Liu, H.* AU - Kanawati, B. AU - Liu, L.* AU - Dong, J.* AU - Li, M.* AU - Huang, J.* AU - Schmitt-Kopplin, P. AU - Cai, Z.* C1 - 24880 C2 - 31711 SP - 5105-5117 TI - Hippocampal metabolomics using ultrahigh-resolution mass spectrometry reveals neuroinflammation from Alzheimer's disease in CRND8 mice. JO - Anal. Bioanal. Chem. VL - 405 IS - 15 PB - Springer PY - 2013 SN - 1618-2642 ER - TY - JOUR AB - Assessing the environmental fate of chiral micropollutants such as herbicides is challenging. The complexity of aquatic systems often makes it difficult to obtain hydraulic mass balances, which is a prerequisite when assessing degradation based on concentration data. Elegant alternatives are concentration-independent approaches like compound-specific isotope analysis or enantiospecific concentration analysis. Both detect degradation-induced changes from ratios of molecular species, either isotopologues or enantiomers. A combination of both-enantioselective stable isotope analysis (ESIA)-provides information on C-13/C-12 ratios for each enantiomer separately. Recently, Badea et al. demonstrated for the first time ESIA for the insecticide alpha-hexachlorocyclohexane. The present study enlarges the applicability of ESIA to polar herbicides such as phenoxy acids: 4-CPP ((RS)-2-(4-chlorophenoxy)-propionic acid), mecoprop (2-(4-chloro-2-methylphenoxy)-propionic acid), and dichlorprop (2-(2,4-dichlorophenoxy)-propionic acid). Enantioselective gas chromatography-isotope ratio mass spectrometry was accomplished with derivatization prior to analysis. Precise carbon isotope analysis (2 sigma a parts per thousand currency signaEuro parts per thousand 0.5aEuro degrees) was obtained with a parts per thousand yen7 ng C on column. Microbial degradation of dichlorprop, 2-(2,4-dichlorophenoxy)-propionic acid by Delftia acidovorans MC1 showed pronounced enantiomer fractionation, but no isotope fractionation. In contrast, Badea et al. observed isotope fractionation, but no enantiomeric fractionation. Hence, the two lines of evidence appear to complement each other. They may provide enhanced insight when combined as ESIA. AU - Maier, M. AU - Qiu, S. AU - Elsner, M. C1 - 23638 C2 - 31269 SP - 2825-2831 TI - Enantioselective Stable Isotope Analysis (ESIA) of polar herbicides. JO - Anal. Bioanal. Chem. VL - 405 IS - 9 PB - Springer PY - 2013 SN - 1618-2642 ER - TY - JOUR AB - Occupational manganese (Mn) overexposure leads to accumulation in the brain and has been shown to cause progressive, permanent, neuro-degenerative damage with syndromes similar to idiopathic Parkinsonism. Mn is transported by an active mechanism across neural barriers (NB) finally into the brain; but to date, modes of Mn neurotoxic action are poorly understood. This paper investigates the relevant Mn-carrier species which are responsible for widely uncontrolled transport across NB. Mn speciation in paired serum/cerebrospinal fluid (CSF) samples was performed by size exclusion chromatography-inductively coupled plasma-dynamic reaction cell-mass spectrometry (SEC-ICP-DRC-MS) and capillary zone electrophoresis coupled to ICP-DRC-MS in a 2D approach for clear identification. For additional species verification, electrospray ionization-Fourier transform ion cyclotron resonance-mass spectrometry was used after SEC-ICP-DRC-MS (second 2D approach). The Mn species from the different sample types were interrelated and correlation coefficients were calculated. In serum protein-bound Mn species like Mn-transferrin/albumin (Mn-Tf/HSA) were dominant, which had the main influence on total Mn in serum if Mn(total) was <1.5 μg/L. Above serum Mn(total) concentration of 1.6 μg/L the serum Mn(total) concentration was correlated with increasing Mn-citrate (Mn-Cit) concentration. In parallel Mn(total) and Mn species in CSF were determined. It turned out that Mn(total) from CSF was about half of Mn(total) in serum; Mn-Tf/HSA was only about 10 % compared to serum. It turned out that above 1.6 μg/L Mn(total) in serum Mn-Cit was not only the leading Mn species in serum but also was the main influencing factor of both Mn(total) and Mn-Cit concentration in CSF. These results were further investigated using two statistical models (orthogonal partial least squares discriminant analysis, canonical discriminant analysis). Both models discriminated the samples in two groups where CSF samples were either correlated to Mn(total) and Mn-Cit (samples with serum Mn(total) > 1,550 ng/L) or correlated to Mn-Tf/HSA (samples with serum Mn(total) < 1,550 ng/L). We conclude that elevated Mn-Cit(serum) could be a valuable marker for increased total Mn in CSF (and brain), i.e., it could be a marker for elevated risk of Mn-dependent neurological disorders such as manganism in occupational health. AU - Michalke, B. AU - Lucio, M. AU - Berthele, A.* AU - Kanawati, B. C1 - 23117 C2 - 30996 SP - 2301-2309 TI - Manganese speciation in paired serum and CSF samples using SEC-DRC-ICP-MS and CE-ICP-DRC-MS. JO - Anal. Bioanal. Chem. VL - 405 IS - 7 PB - Springer PY - 2013 SN - 1618-2642 ER - TY - JOUR AB - Infections with Chlamydia pneumoniae cause several respiratory diseases, such as community-acquired pneumonia, bronchitis or sinusitis. Here, we present an integrated non-targeted metabolomics analysis applying ultra-high-resolution mass spectrometry and ultra-performance liquid chromatography mass spectrometry to determine metabolite alterations in C. pneumoniae-infected HEp-2 cells. Most important permutations are elaborated using uni- and multivariate statistical analysis, logD retention time regression and mass defect-based network analysis. Classes of metabolites showing high variations upon infection are lipids, carbohydrates and amino acids. Moreover, we observed several non-annotated compounds as predominantly abundant after infection, which are promising biomarker candidates for drug-target and diagnostic research. AU - Müller, C. AU - Dietz, I.* AU - Tziotis, D. AU - Moritz, F. AU - Rupp, J.* AU - Schmitt-Kopplin, P. C1 - 24879 C2 - 31710 SP - 5119-5131 TI - Molecular cartography in acute Chlamydia pneumoniae infections - a non-targeted metabolomics approach. JO - Anal. Bioanal. Chem. VL - 405 IS - 15 PB - Springer PY - 2013 SN - 1618-2642 ER - TY - JOUR AB - Catecholamines play essential roles in several physiological processes in vertebrates as well as in invertebrates. While several studies have shown the presence of these substances in surface water invertebrates, their occurrence in groundwater fauna is unproven. In the present study, the presence of different catecholamines (i.e., noradrenaline, adrenaline, and dopamine) in individual specimens of groundwater amphipods of the genus Niphargus (mostly Niphargus inopinatus) was investigated via two independent analytical methods: HPLC/EcD and UPLC/TOF-MS. Mean values for catecholamine levels were 533 pg mg(-1) fresh weight for noradrenaline, 314 pg mg(-1) for adrenaline, and 16.4 ng mg(-1) for dopamine. The optimized protocol allowed the detection of CAs in single organisms of less than 1 mg fresh weight. Catecholamine concentration patterns in groundwater invertebrates are briefly discussed here with respect to their evolutionary adaptation to an environmentally stable, energy-poor habitat. AU - Pfister, G. AU - Rieb, J. AU - Avramov, M. AU - Rock, T. AU - Griebler, C. AU - Schramm, K.-W. C1 - 24915 C2 - 31714 SP - 5571-5582 TI - Detection of catecholamines in single specimens of groundwater amphipods. JO - Anal. Bioanal. Chem. VL - 405 IS - 16 PB - Springer PY - 2013 SN - 1618-2642 ER - TY - JOUR AB - Electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure photo-ionization (APPI) are the most important techniques for the ionization of liquid samples. However, working under atmospheric pressure conditions, all these techniques involve some chemical rather than purely physical processes, and therefore, side reactions often yield to matrix-dependent ionization efficiencies. Here, a system is presented that combines both soft single-photon ionization (SPI) and hard 70 eV electron impact ionization (EI) of dissolved compounds under vacuum conditions. A quadrupole mass spectrometer was modified to enable direct EI, a technique developed by Cappiello et al. to obtain library-searchable EI mass spectra as well as soft SPI mass spectra of sample solutions. An electron beam-pumped rare gas excimer lamp working at 126 nm was used as well as a focusable vacuum UV light source for single-photon ionization. Both techniques, EI and SPI, were applied successfully for flow injection experiments providing library-matchable EI fragment mass spectra and soft SPI mass spectra, showing dominant signals for the molecular ion. Four model compounds were analyzed: hexadecane, propofol, chlorpropham, and eugenol, with detection limits in the picomolar range. This novel combination of EI and SPI promises great analytical benefits, thanks to the possibility of combining database alignment for EI data and molecular mass information provided by SPI. Possible applications for the presented ionization technology system are a matrix-effect-free detection and a rapid screening of different complex mixtures without time-consuming sample preparation or separation techniques (e.g., for analysis of reaction solutions in combinatorial chemistry) or a switchable hard (EI) and soft (SPI) MS method as detection step for liquid chromatography. AU - Schepler, C. AU - Sklorz, M. AU - Passig, J. AU - Famiglini, G.* AU - Cappiello, A.* AU - Zimmermann, R. C1 - 26232 C2 - 32135 SP - 6953-6957 TI - Flow injection of liquid samples to a mass spectrometer with ionization under vacuum conditions: A combined ion source for single-photon and electron impact ionization. JO - Anal. Bioanal. Chem. VL - 405 IS - 22 PB - Springer PY - 2013 SN - 1618-2642 ER - TY - JOUR AB - Environmental degradation of organic micropollutants is difficult to monitor due to their diffuse and ubiquitous input. Current approaches-concentration measurements over time, or daughter-to-parent compound ratios-may fall short, because they do not consider dilution, compound-specific sorption characteristics or alternative degradation pathways. Compound-specific isotope analysis (CSIA) offers an alternative approach based on evidence from isotope values. Until now, however, the relatively high limits for precise isotope analysis by gas chromatography-isotope ratio mass spectrometry (GC-IRMS) have impeded CSIA of sub-microgram-per-liter scale micropollutant concentrations in field samples. This study presents the first measurements of C and N isotope ratios of the herbicide atrazine and its metabolite desethylatrazine at concentrations of 100 to 1,000 ng/L in natural groundwater samples. Solid-phase extraction and preparative HPLC were tested and validated for preconcentration and cleanup of groundwater samples of up to 10 L without bias by isotope effects. Matrix interferences after solid-phase extraction could be greatly reduced by a preparative HPLC cleanup step prior to GC-IRMS analysis. Sensitivity was increased by a factor of 6 to 8 by changing the injection method from large-volume to cold-on-column injection on the GC-IRMS system. Carbon and nitrogen isotope values of field samples showed no obvious correlation with concentrations or desethylatrazine-to-atrazine ratios. Contrary to expectations, however, delta (13) C values of desethylatrazine were consistently less negative than those of atrazine from the same sites. Potentially, this line of evidence may contain information about further desethylatrazine degradation. In such a case, the common practice of using desethylatrazine-to-atrazine ratios would underestimate natural atrazine degradation. AU - Schreglmann, K. AU - Hoeche, M. AU - Steinbeiss, S. AU - Reinnicke, S. AU - Elsner, M. C1 - 23639 C2 - 31268 SP - 2857-2867 TI - Carbon and nitrogen isotope analysis of atrazine and desethylatrazine at sub-microgram per liter concentrations in groundwater. JO - Anal. Bioanal. Chem. VL - 405 IS - 9 PB - Springer PY - 2013 SN - 1618-2642 ER - TY - JOUR AB - Se speciation was performed in 24 individual paired serum and cerebrospinal fluid (CSF) samples from neurologically healthy persons. Strong anion exchange (SAX) separation, coupled to inductively coupled plasma-dynamic reaction cell-mass spectrometry (ICP-DRC-MS), was employed. Species identification was done by standard matched retention time, standard addition and by size exclusion chromatography followed from SAX (2-D SEC-SAX-ICP-DRC-MS) and by SAX followed from CE-ICP-DRC-MS (2-D SAX-CE-ICP-DRC-MS). Limit of detection (LoD, 3 x standard deviation (SD) of noise) was in the range of 0.026-0.031 mu g/L for all investigated species and thus was set uniformly to 0.032 mu g/L. Quality control for total Se determination was performed by analysing control materials "human serum" and "urine", where determined values met target values. Several Se species were found in both sample types having following median values (sequence: serum/CSF, each in mu g Se/L): total Se, 58.39/0.86; selenoprotein P (SePP), 5.19/0.47; Se-methionine (SeM), 0.23/< LoD; glutathione peroxidase (GPx), 4.2/0.036; thioredoxinreductase (TrxR), 1.64/0.035; Se IV, 12.25/0.046; Se-human serum albumin (Se-HSA), 18.03/0.068. Other Se species, such as Se-cystine (SeC), Se VI and up to four non-identified compounds were monitored (if ever) only in very few samples usually close to LoD. Therefore, their median values were < LoD. Linear relationships based on median values provide information about Se-species passage across neural barriers (NB): SePP-serum is significantly correlated to total Se-serum when the latter was > 65 mu g/L; however, SePP-CSF appeared independent of SePP-serum. For Se-HSA(-serum) versus (vs.) Se-HSA(-CSF), a weak linear relationship was found (r (2) = 0.1722). On the contrary, for anti-oxidative Se-enzymes, higher r (2) values were calculated: GPx(-serum) vs. GPx(-CSF), r (2) = 0.3837; TrxR(-serum) vs. TrxR(-CSF), r (2) = 0.6293. Q (-Se-species) values (= ratios of CSF-Se-species/serum(-Se-species)) were compared with the Q (-Alb) value (HSA(-CSF)/HSA(-serum) = clinical index of NB integrity) for deeper information about NB passage of Se species. The Q (-Se-HSA) value (3.8 x 10(-3)) was in accordance to the molecular mass dependent restriction at NB (Q (-Alb) at 5.25 x 10(-3)). Increased Q values were seen for TrxR (21.3 x 10(-3)) and GPx (8.3 x 10(-3)) which are not (completely) explained by molecular size. For these two anti-oxidative Se-enzymes (GPx, TrxR), we hypothesize that there might be either a facilitated diffusion across NB or they might be additionally synthesized in the brain. AU - Solovyev, N.* AU - Berthele, A.* AU - Michalke, B. C1 - 23151 C2 - 31010 SP - 1875-1884 TI - Selenium speciation in paired serum and cerebrospinal fluid samples. JO - Anal. Bioanal. Chem. VL - 405 IS - 6 PB - Springer PY - 2013 SN - 1618-2642 ER - TY - JOUR AB - Compound-specific isotope analysis (CSIA) is an important tool for the identification of contaminant sources and transformation pathways, but it is rarely applied to emerging aquatic micropollutants owing to a series of instrumental challenges. Using four different benzotriazole corrosion inhibitors and its derivatives as examples, we obtained evidence that formation of organometallic complexes of benzotriazoles with parts of the instrumentation impedes isotope analysis. Therefore, we propose two strategies for accurate C and N measurements of polar organic micropollutants by gas chromatography isotope ratio mass spectrometry (GC/IRMS). Our first approach avoids metallic components and uses a Ni/Pt reactor for benzotriazole combustion while the second is based on the coupling of online methylation to the established GC/IRMS setup. Method detection limits for on-column injection of benzotriazole, as well as its 1-CH-, 4-CH-, and 5-CH-substituted species were 0.1-0.3 mM and 0.1-1.0 mM for delta C-13 and delta N-15 analysis respectively, corresponding to injected masses of 0.7-1.8 nmol C and 0.4-3.0 nmol N, respectively. The Ni/Pt reactor showed good precision and was very long-lived (1000 successful measurements). Coupling isotopic analysis to offline solid-phase extraction enabled benzotriazole-CSIA in tap water, wastewater treatment effluent, activated sludge, and in commercial dishwashing products. A comparison of C and N values from different benzotriazoles and benzotriazole derivatives, both from commercial standards and in dishwashing detergents, reveals the potential application of the proposed method for source apportionment. AU - Spahr, S.* AU - Huntscha, S.* AU - Bolotin, J.* AU - Maier, M. AU - Elsner, M. AU - Hollender, J.* AU - Hofstetter, T.B.* C1 - 23643 C2 - 31266 SP - 2843-2856 TI - Compound-specific isotope analysis of benzotriazole and its derivatives. JO - Anal. Bioanal. Chem. VL - 405 IS - 9 PB - Springer PY - 2013 SN - 1618-2642 ER - TY - JOUR AB - In this study, the chemical composition of sidestream smoke (SSS) emissions of cigarettes are characterised using a laser-based single-photon ionisation time-of-flight mass spectrometer. SSS is generated from various cigarette types (2R4F research cigarette; Burley, Oriental and Virginia single-tobacco-type cigarettes) smoked on a single-port smoking machine and collected using a so-called fishtail chimney device. Using this setup, a puff-resolved quantification of several SSS components was performed. Investigations of the dynamics of SSS emissions show that concentration profiles of various substances can be categorised into several groups, either depending on the occurrence of a puff or uninfluenced by the changes in the burning zone during puffing. The SSS emissions occurring directly after a puff strongly resemble the composition of mainstream smoke (MSS). In the smouldering phase, clear differences between MSS and SSS are observed. The changed chemical profiles of SSS and MSS might be also of importance on environmental tobacco smoke which is largely determined by SSS. Additionally, the chemical composition of the SSS is strongly affected by the tobacco type. Hence, the higher nitrogen content of Burley tobacco leads to the detection of increased amounts of nitrogen-containing substances in SSS. AU - Streibel, T. AU - Mitschke, S. AU - Adam, T. AU - Zimmermann, R. C1 - 26248 C2 - 32143 SP - 7071-7082 TI - Time-resolved analysis of the emission of Sidestream Smoke (SSS) from cigarettes during smoking by Photo Ionisation/Time-Of-Flight Mass Spectrometry (PI-TOFMS): Towards a better description of environmental tobacco smoke. JO - Anal. Bioanal. Chem. VL - 405 IS - 22 PB - Springer PY - 2013 SN - 1618-2642 ER - TY - JOUR AB - Comprehensive multi-dimensional hyphenation of a thermogravimetry device (i.e. a thermobalance) to gas chromatography and single photon ionization-time-of-flight mass spectrometry (TG-GC×SPI-MS) has been used to investigate two crude oil samples of different geographical origin. The source of the applied vacuum ultraviolet radiation is an electron beam pumped rare gas excimer lamp (EBEL). The soft photoionization favors the formation of molecular ions. Introduction of a fast, rapidly modulated gas chromatographic separation step in comparison with solely TG-SPI-MS enables strongly enhanced detection especially with such highly complex organic matrices as crude oil. In contrast with former TG-SPI-MS measurements, separation and identification of overlying substances is possible because of different GC retention times. The specific contribution of isobaric compounds to one mass signal is determined for alkanes, naphthalenes, alkylated benzenes, and other compounds. AU - Wohlfahrt, S. AU - Fischer, M. AU - Saraji-Bozorgzad, M.* AU - Matuschek, G. AU - Streibel, T.* AU - Post, E.* AU - Denner, T.* AU - Zimmermann, R. C1 - 26264 C2 - 32151 SP - 7107-7116 TI - Rapid comprehensive characterization of crude oils by thermogravimetry coupled to fast modulated gas chromatography-single photon ionization time-of-flight mass spectrometry. JO - Anal. Bioanal. Chem. VL - 405 IS - 22 PB - Springer PY - 2013 SN - 1618-2642 ER - TY - SER AB - The article describes how the topical issue of the journal Analytical and Bioanalytical Chemistry (ABC) is devoted to Photo Ionization in Mass Spectrometry. A large variety of widely used analytical methods and technologies evolved from these initial studies on ionization by either photon molecule or laser pulse surface interactions. A schematic time-of-flight mass spectrometer and some photo ionization (PI) techniques used in analytical mass spectrometry are depicted in the article. The scientific contributions in this special issue on photo ionization mass spectrometry are ordered according to the type of contribution. The introduction of the paper in this editorial, however refers the samples matrix and the ionization region pressure. Starting with solid and particulate samples, using laser desorption ionization (LDI), matrix-assisted laser desorption/ionization (MALDI), and finally LD (laser desorption) for sampling of surfaces and aerosol particles. AU - Zimmermann, R. A2 - Zimmermann, R. C1 - 27525 C2 - 32717 SP - 6901-6905 TI - Photo ionisation in mass spectrometry: Light, selectivity and molecular ions. JO - Anal. Bioanal. Chem. VL - 405 IS - 22 PB - Springer PY - 2013 SN - 1618-2642 ER - TY - JOUR AB - Resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOF-MS) is a robust method for real-time analysis of monocyclic and polycyclic aromatic hydrocarbons in complex emissions. A mobile system has been developed which enables direct analysis on site. In this paper, we utilize a multicomponent calibration scheme based on the analytes' photo-ionisation cross-sections relative to a calibrated species. This allows semi-quantification of a great number of components by only calibrating one compound of choice, here toluene. The cross-sections were determined by injecting nebulised solutions of aromatic compounds into the TOF-MS ion source with the help of a HPLC pump. Then, REMPI-TOF-MS was implemented at various chassis dynamometers and test cells and the exhaust of the following vehicles and engines investigated: a compression ignition light-duty (LD) passenger car, a compression ignition LD van, two spark ignition LD passenger cars, 2 two-stroke mopeds, and a two-stroke engine of a string gas trimmer. The quantitative time profiles of benzene are shown. The results indicate that two-stroke engines are a significant source for toxic and cancerogenic compounds. Air pollution and health effects caused by gardening equipment might still be underestimated. AU - Adam, T.W.* AU - Clairotte, M.* AU - Streibel, T.* AU - Elsasser, M. AU - Pommeres, A.* AU - Manfredi, U.* AU - Carriero, M.* AU - Martini, G.* AU - Sklorz, M.* AU - Krasenbrink, A.* AU - Astorga, C.* AU - Zimmermann, R. C1 - 8234 C2 - 30034 SP - 273-276 TI - Real-time analysis of aromatics in combustion engine exhaust by Resonance-Enhanced Multiphoton Ionisation Time-Of-Flight Mass Spectrometry (REMPI-TOF-MS): A robust tool for chassis dynamometer testing. JO - Anal. Bioanal. Chem. VL - 404 IS - 1 PB - Springer PY - 2012 SN - 1618-2642 ER - TY - JOUR AB - A coupling between a cigarette smoking simulator and a time-of-flight mass spectrometer was constructed to allow investigation of tobacco smoke formation under simulated burning conditions. The cigarette smoking simulator is designed to burn a sample in close approximation to the conditions experienced by a lit cigarette. The apparatus also permits conditions outside those of normal cigarette burning to be investigated for mechanistic understanding purposes. It allows control of parameters such as smouldering and puff temperatures, as well as combustion rate and puffing volume. In this study, the system enabled examination of the effects of "smoking" a cigarette under a nitrogen atmosphere. Time-of-flight mass spectrometry combined with a soft ionisation technique is expedient to analyse complex mixtures such as tobacco smoke with a high time resolution. The objective of the study was to separate pyrolysis from combustion processes to reveal the formation mechanism of several selected toxicants. A purposely designed adapter, with no measurable dead volume or memory effects, enables the analysis of pyrolysis and combustion gases from tobacco and tobacco products (e.g. 3R4F reference cigarette) with minimum aging. The combined system demonstrates clear distinctions between smoke composition found under air and nitrogen smoking atmospheres based on the corresponding mass spectra and visualisations using principal component analysis. AU - Busch, C.* AU - Streibel, T. AU - Liu, C.* AU - McAdam, K.G.* AU - Zimmermann, R. C1 - 7520 C2 - 29779 SP - 419-430 TI - Pyrolysis and combustion of tobacco in a cigarette smoking simulator under air and nitrogen atmosphere. JO - Anal. Bioanal. Chem. VL - 403 IS - 2 PB - Springer PY - 2012 SN - 1618-2642 ER - TY - JOUR AB - Compound-specific stable-isotope analysis (CSIA) has greatly facilitated assessment of sources and transformation processes of organic pollutants. Multielement isotope analysis is one of the most promising applications of CSIA because it even enables distinction of different transformation pathways. This review introduces the essential features of continuous-flow isotope-ratio mass spectrometry (IRMS) and highlights current challenges in environmental analysis as exemplified for the isotopes of nitrogen, hydrogen, chlorine, and oxygen. Strategies and recent advances to enable isotopic measurements of polar contaminants, for example pesticides or pharmaceuticals, are discussed with special emphasis on possible solutions for analysis of low concentrations of contaminants in environmental matrices. Finally, we discuss different levels of calibration and referencing and point out the urgent need for compound-specific isotope standards for gas chromatography-isotope-ratio mass spectrometry (GC-IRMS) of organic pollutants. AU - Elsner, M. AU - Jochmann, M.A.* AU - Hofstetter, T.B.* AU - Hunkeler, D.* AU - Bernstein, A.* AU - Schmidt, T.C.* AU - Schimmelmann, A.* C1 - 7588 C2 - 29857 SP - 2471-2491 TI - Current challenges in compound-specific stable isotope analysis of environmental organic contaminants. JO - Anal. Bioanal. Chem. VL - 403 IS - 9 PB - Springer PY - 2012 SN - 1618-2642 ER - TY - JOUR AB - Procalcitonin (PCT)-a diagnostic serum parameter for bacterial infection and sepsis-is of great interest in the field of biosensors for point-of-care testing. Its detection needs specific biological recognition elements, such as antibodies. Herein, we describe the development and characterization of rat monoclonal antibodies (mAbs) for PCT, and their application in enzyme-linked immunosorbent assays (ELISAs) for the determination of PCT in patient serum samples. From about 50 mAbs, two mAbs, CALCA 2F3 and CALCA 4A6, were selected as a pair with high affinity for PCT in sandwich immunoassays. Both mAbs could be used either as capture or as detection mAb. They were Protein G-purified and biotinylated when used as detection mAb. The setup of two sandwich ELISAs with standards of human recombinant (hr) PCT, using either CALCA 2F3 (assay A) or CALCA 4A6 (assay B) as capture mAbs and the biotinylated mAbs CALCA 4A6 or CALCA 2F3, respectively, as detection mAbs, led to highly specific determinations of PCT without cross-reactivity to calcitonin and katacalcin. Test midpoints (IC(50)) of both assays were determined for hrPCT standards in 4% (w/v) human serum albumin and found with 2.5 (assay A) and 2.7 μg L(-1) (assay B). With both sandwich ELISAs a collection of eight patient serum samples have been determined in comparison to the determination by the Elecsys BRAHMS PCT assay. Good correlations between our prototype ELISAs and the BRAHMS assay could be demonstrated (R (2): assay A, 0.996 and assay B, 0.990). The use of these newly developed anti-PCT mAbs should find broad applications in immunosensors for point-of-care diagnostics of sepsis and systemic inflammation processes. AU - Kremmer, E. AU - Meyer, K.* AU - Grässer, F.A.* AU - Flatley, A. AU - Kösters, M.* AU - Luppa, P.B.* AU - Krämer, P.M. C1 - 6268 C2 - 29113 SP - 989-995 TI - A new strategy for the development of monoclonal antibodies for the determination of human procalcitonin in serum samples. JO - Anal. Bioanal. Chem. VL - 402 IS - 2 PB - Springer PY - 2012 SN - 1618-2642 ER - TY - JOUR AB - An innovative analytical method based on high-performance liquid chromatography and atmospheric pressure chemical ionization magnetic sector mass spectrometry was developed and optimized to determine trace concentrations of 11 compounds belonging to the group of the seldom-analyzed oxy-PAHs (phenanthrene-9,10-dione, chrysene-5,6-dione, benzo[a]pyrene-4,5-dione, benzo[a]pyrene-1,6-dione, benzo[a]pyrene-3,6-dione, benzo[a]pyrene-6,12-dione, 4-oxa-benzo[def]chrysene-5-one, pyrene-1-carboxaldehyde, benzo[de]anthracene-7-one, benzo[a]anthracene-7,12-dione, and napthacene-5,12-dione) on airborne particulate matter (PM(10)). The mass spectrometer was operated in multiple ion detection mode, allowing for selective accurate mass detection (mass resolution of 12,000 full width at half maximum) of the oxy-PAHs characteristic ions. Optimization of both the vaporizer (450 °C) and capillary temperature (350 °C) resulted into instrumental detection limits in the range between 7 (benzo[a]pyrene-1,6-dione) and 926 pg (benzo[a]anthracene-7,12-dione). The advanced pressurized liquid extraction (PLE) and the more traditionally used ultrasonic extraction (USE) were compared using ethyl acetate as an extraction solvent. For both techniques, high recoveries from spiked quartz fiber filters (PLE, 82-110%; USE, 67-97%) were obtained. Recoveries obtained from real PM(10) samples were also high (76-107%), and no significant matrix effects (ME) on the ionization process (enhancement or suppression) were found (ME, 89-123%). Method limits of quantification (S/N = 10) were in the range between 2 and 336 pg/m(3). This method was used to analyze real PM samples collected at several urban and rural locations in the Antwerp area. For the first time, concentrations for Belgium are provided. Concentrations of individual oxy-PAHs are in the lower pictograms per cubic meter to 6 ng/m(3) range. High concentration differences between individual compounds are found as exemplified by the 75th percentile of the phenanthrene-9,10-dione and benzo[de]anthracene-7-one concentrations being a factor of 4 to 22 higher compared with the other target oxy-PAHs. AU - Walgraeve, C.* AU - Demeestere, K.* AU - de Wispelaere, P.* AU - Dewulf, J.* AU - Lintelmann, J. AU - Fischer, K. AU - van Langenhove, H.* C1 - 7157 C2 - 29497 SP - 1697-1711 TI - Selective accurate-mass-based analysis of 11 oxy-PAHs on atmospheric particulate matter by pressurized liquid extraction followed by high-performance liquid chromatography and magnetic sector mass spectrometry. JO - Anal. Bioanal. Chem. VL - 402 IS - 4 PB - Springer PY - 2012 SN - 1618-2642 ER - TY - JOUR AB - The polyphenols, for example stilbenes and flavonoids, are an important family of compounds present in grapes and wines. Several studies have shown that stilbenes are antioxidants and cancer-preventing agents. For the first time, eight natural stilbenes (trans-resveratrol, trans-piceid, cis-piceid, trans-astringin, trans-piceatannol, (+)-trans-ε-viniferin, pallidol, and hopeaphenol), isolated and purified from Vitis vinifera, were simultaneously analysed by ultra-high-pressure liquid chromatography coupled with photodiode-array detection. Separation of the stilbenes by UHPLC was optimized with the assistance of "Quality-by-Design" commercial software. Four different reversed-phase columns packed with 1.5-1.7-μm particles were tested and compared for their retention behaviour and separation efficiency. On the basis of the performance characteristics determined, the VisionHT C18 HL column was selected for the stilbenes studied, because resolution of the critical pair was 1.5 with a peak width of 2-4 s. The optimized method resulted in highly repeatable retention times (RSD 0.03-0.07%), peak areas (RSD 3-6%), and linear ranges were between 0.005 and 50 mg L-1 for most of the compounds. All stilbenes, except trans-astringin, trans-piceatannol, and pallidol were identified and quantified in Burgundy red wines at different concentrations after direct injection of the wines. [Figure not available: see fulltext.] © 2011 Springer-Verlag. AU - Boutegrabet, L. AU - Fekete, A. AU - Hertkorn, N. AU - Papastamoulis, Y.* AU - Waffo-Téguo, P.* AU - Mérillon, J.M.* AU - Jeandet, P.* AU - Gougeon, R.D.* AU - Schmitt-Kopplin, P. C1 - 6542 C2 - 28854 SP - 1513-1521 TI - Determination of stilbene derivatives in Burgundy red wines by ultra-high-pressure liquid chromatography. JO - Anal. Bioanal. Chem. VL - 401 IS - 5 PB - Springer PY - 2011 SN - 1618-2642 ER - TY - JOUR AB - Normalization is critically important for the proper interpretation of matrix-assisted laser desorption/ionization (MALDI) imaging datasets. The effects of the commonly used normalization techniques based on total ion count (TIC) or vector norm normalization are significant, and they are frequently beneficial. In certain cases, however, these normalization algorithms may produce misleading results and possibly lead to wrong conclusions, e.g. regarding to potential biomarker distributions. This is typical for tissues in which signals of prominent abundance are present in confined areas, such as insulin in the pancreas or β-amyloid peptides in the brain. In this work, we investigated whether normalization can be improved if dominant signals are excluded from the calculation. Because manual interaction with the data (e.g., defining the abundant signals) is not desired for routine analysis, we investigated two alternatives: normalization on the spectra noise level or on the median of signal intensities in the spectrum. Normalization on the median and the noise level was found to be significantly more robust against artifact generation compared to normalization on the TIC. Therefore, we propose to include these normalization methods in the standard "toolbox" of MALDI imaging for reliable results under conditions of automation. AU - Deininger, S.O.* AU - Cornett, D.S.* AU - Paape, R.* AU - Becker, M.* AU - Pineau, C.* AU - Rauser, S. AU - Walch, A.K. AU - Wolski, E.* C1 - 6507 C2 - 28832 SP - 167-181 TI - Normalization in MALDI-TOF imaging datasets of proteins: Practical considerations. JO - Anal. Bioanal. Chem. VL - 401 IS - 1 PB - Springer PY - 2011 SN - 1618-2642 ER - TY - JOUR AB - To date, no reference method for the extraction of labile Mn species from biological tissues is published which provides sufficient extraction efficiency combined with monitoring speciation. Here, an extraction method is reported using cryogenic conditions (+N) under inert gas atmosphere. Fresh brain and liver tissues were used, then stored either 1 day (+N) or 1 month in N(2liq) (+N 1 m) to evaluate degradation effects during long-term storage. Both attempts were compared to a previous extraction method (-N) using neither N(2liq) nor storage ability. Mn and Fe concentrations in extracts and pellets were determined with inductively coupled plasma (ICP)-atomic emission spectroscopy (AES) and compared to acid digests of the same sample. Element ratios of extracts/digest indicated the extraction efficiency, which was increased from 17% (-N) to 26% (+N) for Mn in brain or from 28% (-N) to 44% (+N) in liver extracts. For Fe species, the increase was only from 40% (-N) to 44% (+N) in brain but from 64% (-N) to 74% (+N) in liver. Size exclusion chromatography (SEC)-ICP-mass spectrometry (MS) was employed to screen for Mn and Fe species pattern in extracts. In brain, surplus extracted Mn (+N, +N 1 m) was assigned to organic Mn species, mainly from the 0.7-4 kDa fraction, while in the liver, it was seen in the 70-80 kDa fraction. Fe speciation was similar for -N and +N methods in brain extracts. In liver, higher amounts of Fe species were extracted from the 140-160 kDa fraction. Storage at -196 °C for 1 month did neither affect Mn speciation in brain nor in liver extracts. Fe species pattern showed a negligible shift (≤5%) from 140-160 to 70-80 kDa fraction in liver extracts stored 1 month in N(2liq). AU - Diederich, J. AU - Michalke, B. C1 - 4407 C2 - 27628 SP - 1799-1806 TI - Enhanced extract preparation of native manganese and iron species from brain and liver tissue. JO - Anal. Bioanal. Chem. VL - 399 IS - 5 PB - Springer PY - 2011 SN - 1618-2642 ER - TY - JOUR AB - The carbonaceous fraction of airborne particulate matter (PM) is of increasing interest due to the adverse health effects they are linked to. Its analytical ascertainment on a molecular level is still challenging. Hence, analysis of carbonaceous fractions is often carried out by determining bulk parameters such as the overall content of organic compounds (OC) and elemental carbon (EC) as well as the total carbon content, TC (sum of OC and EC), however, no information about the individual substances or substance classes, of which the single fractions consist can be obtained. In this work, a carbon analyzer and a photo-ionization time-of-flight mass spectrometer (PI-TOF-MS) were hyphenated to investigate individual compounds especially from the OC fractions. The carbon analyzer enables the stepwise heating of particle samples and provides the bulk parameters. With the PI-TOF-MS, it is possible to detect the organic compounds released during the single-temperature steps due to soft ionization and fast detection of the molecular ions. The hyphenation was designed, built up, characterized by standard substances, and applied to several kinds of samples, such as ambient aerosol, gasoline, and diesel emission as well as wood combustion emission samples. The ambient filter sample showed a strong impact of wood combustion markers. This was revealed by comparison to the product pattern of the similar analysis of pure cellulose and lignin and the wood combustion PM. At higher temperatures (450 °C), a shift to smaller molecules occurred due to the thermal decomposition of larger structures of oligomeric or polymeric nature comparable to lignocelluloses and similar oxygenated humic-like substances. Finally, particulate matter from gasoline and diesel containing 10% biodiesel vehicle exhaust has been analyzed. Gasoline-derived PM exhibited large polycyclic aromatic hydrocarbons, whereas diesel PM showed a much higher total organic content. The detected pattern revealed a strong influence of the biodiesel content on the nature of the particulate organic material. AU - Grabowsky, J.* AU - Streibel, T.* AU - Sklorz, M.* AU - Chow, J.C.* AU - Watson, J.G.* AU - Mamakos, A.* AU - Zimmermann, R. C1 - 6814 C2 - 29309 SP - 3153-3164 TI - Hyphenation of a carbon analyzer to photo-ionization mass spectrometry to unravel the organic composition of particulate matter on a molecular level. JO - Anal. Bioanal. Chem. VL - 401 IS - 10 PB - Springer PY - 2011 SN - 1618-2642 ER - TY - JOUR AB - Breath analysis could offer a non-invasive means of intravenous drug monitoring if robust correlations between drug concentrations in breath and blood can be established. In this study, propofol blood and breath concentrations were determined in an animal model under varying physiological conditions. Propofol concentrations in breath were determined by means of two independently calibrated analytical methods: continuous, real-time proton transfer reaction mass spectrometry (PTR-MS) and discontinuous solid-phase micro-extraction coupled with gas chromatography mass spectrometry (SPME-GC-MS). Blood concentrations were determined by means of SPME-GC-MS. Effects of changes in pulmonary blood flow resulting in a decreased cardiac output (CO) and effects of dobutamine administration resulting in an increased CO on propofol breath concentrations and on the correlation between propofol blood and breath concentrations were investigated in seven acutely instrumented pigs. Discontinuous propofol determination in breath by means of alveolar sampling and SPME-GC-MS showed good agreement (R(2)=0.959) with continuous alveolar real-time measurement by means of PTR-MS. In all investigated animals, increasing cardiac output led to a deterioration of the relationship between breath and blood propofol concentrations (R(2)=0.783 for gas chromatography-mass spectrometry and R(2)=0.795 for PTR-MS). Decreasing pulmonary blood flow and cardiac output through banding of the pulmonary artery did not significantly affect the relationship between propofol breath and blood concentrations (R(2)>0.90). Estimation of propofol blood concentrations from exhaled alveolar concentrations seems possible by means of different analytical methods even when cardiac output is decreased. Increases in cardiac output preclude prediction of blood propofol concentration from exhaled concentrations. AU - Kamysek, S.* AU - Fuchs, P.* AU - Schwoebel, H. AU - Roesner, J.P.* AU - Kischkel, S.* AU - Wolter, K.* AU - Loeseken, C.* AU - Schubert, J.K.* AU - Miekisch, W.* C1 - 6827 C2 - 29324 SP - 2093-2102 TI - Drug detection in breath: Effects of pulmonary blood flow and cardiac output on propofol exhalation. JO - Anal. Bioanal. Chem. VL - 401 IS - 7 PB - Springer PY - 2011 SN - 1618-2642 ER - TY - JOUR AB - The on-line analysis of single aerosol particles with mass spectrometrical methods is an important tool for the investigation of aerosols. Often, a single laser pulse is used for one-step laser desorption/ionisation of aerosol particles. Resulting ions are detected with time-of-flight mass spectrometry. With this method, the detection of inorganic compounds is possible. The detection of more fragile organic compounds and carbon clusters can be accomplished by separating the desorption and the ionisation in two steps, e.g. by using two laser pulses. A further method is, using a heated metal surface for thermal desorption of aerosol particles. If an ultraviolet laser is used for ionisation, a selective ionisation of polycyclic aromatic hydrocarbons (PAH) and alkylated PAH is possible via a resonance-enhanced multiphoton-ionisation process. Laser velocimetry allows individual laser triggering for single particles and additionally delivers information on aerodynamic particle diameters. It was shown that particles deriving from different combustion sources can be differentiated according to their PAH patterns. For example, retene, a C(4)-alkylated phenanthrene derivative, is a marker for the combustion of coniferous wood. In this paper, the first field application of a thermal desorption resonance-enhanced multiphoton-ionisation single particle time-of-flight mass spectrometer during a measurement campaign in Augsburg, Germany in winter 2010 is presented. Larger PAH-containing particles (i.e. with aerodynamic diameters larger than 1 μm), which are suspected to be originated by re-suspension processes of agglomerated material, were in the focus of the investigation. Due to the low concentration of these particles, an on-line virtual impactor enrichment system was used. The detection of particle-bound PAH in ambient particles in this larger size region was possible and in addition, retene could be detected on several particles, which allows to identify wood combustion as generic source of these particles. The observed diurnal distribution of these larger particles, however, support the origin by traffic induced re-suspension of sedimented/agglomerated material. AU - Oster, M. AU - Elsasser, M. AU - Schnelle-Kreis, J. AU - Zimmermann, R. C1 - 6740 C2 - 29192 CY - Heidelberg, Germany SP - 3173-3182 TI - First field application of a thermal desorption resonance-enhanced multiphoton-ionisation single particle time-of-flight mass spectrometer for the on-line detection of particle-bound polycyclic aromatic hydrocarbons. JO - Anal. Bioanal. Chem. VL - 401 IS - 10 PB - Springer PY - 2011 SN - 1618-2642 ER - TY - JOUR AB - Direct thermal desorption and in-situ derivatization thermal desorption methods in conjunction with gas chromatography time-of-flight mass spectrometry have been characterized and evaluated for analysis of trace components from filters loaded with ambient particulate matter (PM). The limits of quantification were in the range of 7-24 pg for n-alkanes, 20 pg for hopanes, and 4-22 pg for polycyclic aromatic hydrocarbons (PAH). The limit of quantification was defined as the minimum amount of substance that conforms to the minimum distinguishable signal plus 9 times the standard deviation of this background signal from PM-loaded filters. The method has been successfully applied to low-volume samples from ambient PM collected with stationary and personal samplers. Stationary samples were collected in winter 2008 and 2010 in Augsburg, Germany. Sample aliquots of 0.2-0.3 m³ from stationary sampling were analyzed. High diurnal variation in concentration and source contribution was found especially during periods with low wind speed and low mixing layer height. High contributions of solid fuel combustion (wood and coal) were found in evening and nighttime samples, leading to peak PAH concentrations at midnight more than 10 times higher than at noon. Finally, the method was applied to samples collected by means of a personal sampler, i.e. a micro aethalometer, in Xi'an, China. Quantitative data on n-alkanes, hopanes, and PAH were obtained from sample volumes of 17 and 24 l. The impact of different sources such as vehicular and biogenic emissions could be distinguished. AU - Schnelle-Kreis, J. AU - Orasche, J. AU - Abbaszade, G. AU - Schäfer, K.* AU - Harlos, D.P.* AU - Hansen, A.D.* AU - Zimmermann, R. C1 - 6741 C2 - 29194 CY - Heidelberg, Germany SP - 3083-3094 TI - Application of direct thermal desorption gas chromatography time-of-flight mass spectrometry for determination of nonpolar organics in low-volume samples from ambient particulate matter and personal samplers. JO - Anal. Bioanal. Chem. VL - 401 IS - 10 PB - Springer PY - 2011 SN - 1618-2642 ER - TY - JOUR AB - Separation of inspiratory, mixed expired and alveolar air is indispensable for reliable analysis of VOC breath biomarkers. Time resolution of direct mass spectrometers often is not sufficient to reliably resolve the phases of a breathing cycle. To realise fast on-line breath monitoring by means of direct MS utilising low-fragmentation soft ionisation, a data processing algorithm was developed to identify inspiratory and alveolar phases from MS data without any additional equipment. To test the algorithm selected breath biomarkers (acetone, isoprene, acetaldehyde and hexanal) were determined by means of quadrupole proton transfer reaction mass spectrometry (PTR-MS) in seven healthy volunteers during exercise on a stationary bicycle. The results were compared to an off-line reference method consisting of controlled alveolar breath sampling in Tedlar® bags, preconcentration by solid-phase micro extraction (SPME), separation and identification by GC-MS. Based on the data processing method, quantitative attribution of biomarkers to inspiratory, alveolar and mixed expiratory phases was possible at any time during the experiment, even under respiratory rates up to 60/min. Alveolar concentrations of the breath markers, measured by PTR-MS ranged from 130 to 2,600 ppb (acetone), 10 to 540 ppb (isoprene), 2 to 31 ppb (acetaldehyde), whereas the concentrations of hexanal were always below the limit of detection (LOD) of 3 ppb. There was good correlation between on-line PTR-MS and SPME-GC-MS measurements during phases with stable physiological parameters but results diverged during rapid changes of heart rate and minute ventilation. This clearly demonstrates the benefits of breath-resolved MS for fast on-line monitoring of exhaled VOCs. AU - Schwoebel, H. AU - Schubert, R.* AU - Sklorz, M. AU - Kischkel, S.* AU - Zimmermann, R. AU - Schubert, JK.* AU - Miekisch, W.* C1 - 6828 C2 - 29325 SP - 2079-2091 TI - Phase-resolved real-time breath analysis during exercise by means of smart processing of PTR-MS data. JO - Anal. Bioanal. Chem. VL - 401 IS - 7 PB - Springer PY - 2011 SN - 1618-2642 ER - TY - JOUR AB - Around the world particulate air pollution represents one of the most urgent problems in environmental health. Numerous epidemiological studies have shown that human health and well-being are substantially impacted by elevated levels of airborne particulate matter (PM) [6–8]. This is well documented, starting with the classical work on the air-pollution-related death toll of the London smog episode in 1952 [1, 2] and the famous six cities study in the USA [3–5] which investigated the influence of ambient particle levels in several polluted US cities on the life expectancy of their inhabitants. Moreover, a meta-analysis of epidemiological data and the measured mass concentrations of fine particulate matter (PM10, i.e. particles with an aerodynamic diameter of less than 10 μm) in Europe by the Clean Air For Europe (CAFE) steering group of the European Commission [9] yielded eye-opening results that generated a colour-coded map of Europe, depicting the estimated loss of life expectancy in AU - Zimmermann, R. C1 - 6829 C2 - 29326 SP - 3041-3044 TI - Ambient aerosols and human health: Working towards a combined analytical and toxicological approach. JO - Anal. Bioanal. Chem. VL - 401 IS - 10 PB - Springer PY - 2011 SN - 1618-2642 ER - TY - JOUR AB - Proton transfer reaction mass spectrometry (PTR-MS) has been used to analyze the volatile organic compounds (VOCs) emitted by in-vitro cultured human cells. For this purpose, two pairs of cancerous and non-cancerous human cell lines were selected:1. lung epithelium cells A-549 and retinal pigment epithelium cells hTERT-RPE1, cultured in different growth media; and 2. squamous lung carcinoma cells EPLC and immortalized human bronchial epithelial cells BEAS2B, cultured in identical growth medium. The VOCs in the headspace of the cell cultures were sampled: 1. online by drawing off the gas directly from the culture flask; and 2. by accumulation of the VOCs in PTFE bags connected to the flask for at least 12 h. The pure media were analyzed in the same way as the corresponding cells in order to provide a reference. Direct comparison of headspace VOCs from flasks with cells plus medium and from flasks with pure medium enabled the characterization of cell-line-specific production or consumption of VOCs. Among all identified VOCs in this respect, the most outstanding compound was m/z = 45 (acetaldehyde) revealing significant consumption by the cancerous cell lines but not by the non-cancerous cells. By applying multivariate statistical analysis using 42 selected marker VOCs, it was possible to clearly separate the cancerous and non-cancerous cell lines from each other. AU - Brunner, C.C. AU - Szymczak, W. AU - Höllriegl, V. AU - Mörtl, S. AU - Oelmez, H.* AU - Bergner, A.* AU - Huber, R.M.* AU - Hoeschen, C. AU - Oeh, U. C1 - 772 C2 - 27237 SP - 2315-2324 TI - Discrimination of cancerous and non-cancerous cell lines by headspace-analysis with PTR-MS. JO - Anal. Bioanal. Chem. VL - 397 IS - 6 PB - Springer PY - 2010 SN - 1618-2642 ER - TY - JOUR AB - Quorum sensing (QS) is a communication mechanism between bacteria using diffusible chemical signaling molecules, which are called autoinducers (AI). By detecting the concentration of quorum sensing molecules through binding to a specific receptor protein, bacteria regulate their gene expressions when the concentration of autoinducers and thus the cell density reaches a threshold level. Many Gram-negative bacteria use acylated homoserine lactones (HSLs) as autoinducers. Because of the broad biological functions of HSLs, interest in detection and analysis of HSLs is increasing with a view to their medical, biotechnological, and agricultural applications. In this study, an anti-HSL antibody-based immunochemical detection method has been developed. Four structurally distinct HSL haptens, named HSL1, HSL2, HSL3, and HSL4, have been designed for antibody and assay development. New rat anti-HSL monoclonal antibodies (mAbs) have been produced in-house and characterized with enzyme-linked immunosorbent assays (ELISA), both in the coating antigen and in the enzyme tracer format. Eight mAbs (HSL1-1A5, HSL1-8E1, HSL1/2-2C10, HSL1/2-4H5, HSL4-4C9, HSL4-5E12, HSL4-5H3, and HSL4-6D3) will be presented in this paper. We demonstrate that the anti-HSL mAbs have distinguished sensitivity and selectivity toward HSLs depending upon their chemical structures. The optimized assays are capable of detecting HSLs in the microgram per liter (low micromolar to nanomolar) range. The best IC(50) (test midpoint) was 134 ± 30 μg L(-1) (n = 54) for N-(3-oxodecanoyl)-L-homoserine lactone (3-oxo-C10-HSL) using mAb HSL1/2-2C10 and HSL1-HRP in the enzyme tracer format. In the coating antigen format, the most selective mAb for N-octanoyl-L-homoserine lactone (C8-HSL) was mAb HSL4-4C9. Additionally, anti-HSL mAbs showed higher sensitivity against hydrolyzed HSLs, namely homoserines. These compounds might also occur under certain biological conditions. This study marks the beginning of new ways for quick and cost-effective HSL detection, requiring small sample amounts (less than 1 mL) and little to no sample preparation. AU - Chen, X. AU - Kremmer, E. AU - Gouzy, M.F. AU - Clausen, E. AU - Starke, M. AU - Wöllner, K. AU - Pfister, G. AU - Hartmann, A. AU - Krämer, P.M. C1 - 4179 C2 - 27719 CY - Berlin [u.a.] SP - 2655-2667 TI - Development and characterization of rat monoclonal antibodies for N-acylated homoserine lactones. JO - Anal. Bioanal. Chem. VL - 398 IS - 6 PB - Springer PY - 2010 SN - 1618-2642 ER - TY - JOUR AB - The Burkholderia cepacia complex (Bcc) employs a quorum sensing (QS) mechanism which is a cell density-dependent bacterial communication system to regulate certain gene expressions. As with many other Gram-negative bacteria, Burkholderia cepacia species use (N-acyl-)homoserine lactones (AHLs or HSLs) as signalling molecules. Because of the essential role of QS in bacterial behavior, the aim of this study was to demonstrate the applicability of our in-house-developed enzyme-linked immunosorbent assays (ELISAs) for the detection of bacterial activities via HSLs in B. cepacia strain LA3 culture supernatants. For this purpose the previously developed monoclonal antibodies (mAbs) HSL1/2-2C10 and HSL1/2-4H5 were exploited. N-3-Oxo-decanoyl-L-homoserine lactone (3-oxo-C10-HSL) was used as main analyte throughout all experiments. With the bacterial culture medium (named ABC medium) a matrix effect in both ELISAs was visible (slight increase in optical density, shift in test midpoints (IC(50)) and working ranges). For example, ELISA with mAb HSL1/2-2C10 and enzyme tracer HSL3-HRP (HSL derivative conjugated to horseradish peroxidase) had an IC(50) of 120 μg L(-1) for 3-oxo-C10-HSL in phosphate-buffered saline versus 372 μg L(-1) in ABC medium. A significant increase of HSLs in B. cepacia strain LA3 culture supernatants after 12 h to 48 h of growth was observed. Although the analytical result of these immunoassays cannot distinguish HSLs from homoserines (HSs), the appearance of these compounds can be easily followed. Hydrolysis and spiking experiments were carried out with these biological samples. According to our knowledge, these are the first immunoassays for the detection of quorum sensing molecules in biological culture supernatants. This study provides a cost-effective, fast, and sensitive analytical method for detection of HSLs/HSs in biological samples without complex sample preparation and will offer a quick idea about B. cepacia activities. The low sample amount requirement (less than 1 mL) constitutes a tremendous advantage for many analytical questions with biological samples. AU - Chen, X.A. AU - Buddrus-Schiemann, K.E.M. AU - Rothballer, M. AU - Krämer, P.M. AU - Hartmann, A. C1 - 2978 C2 - 27966 SP - 2669-2676 TI - Detection of quorum sensing molecules in Burkholderia cepacia culture supernatants with enzyme-linked immunosorbent assays. JO - Anal. Bioanal. Chem. VL - 398 IS - 6 PB - Springer PY - 2010 SN - 1618-2642 ER - TY - JOUR AB - The hydrolysis of the herbicide safener mefenpyrdiethyl (1-(2, 4-dichlorophenyl)-4, 5-dihydro-5-methyl-1H-pyrazole-3,5-dicarboxylic acid diethyl ester) was investigated in aqueous solutions in the pH range from 2 to 9 and the temperature range from 298 to 323 K. The kinetics of hydrolysis were pseudo first order and were found to be strongly pH and temperature dependent. While near-constant in acidic medium, the hydrolysis rates strongly increased in alkaline pH, and total hydrolysis was observed at pH 11. Two main hydrolysis products, mefenpyrethyl (monoester) and mefenpyr (dicarboxylic acid) were isolated by ultrahigh-pressure liquid chromatography (UHPLC) and characterized using high-resolution Fourier transform ion cyclotron resonance mass spectroscopy (ICR-FT/MS) as well as H-1, C-13 and 2D NMR analyses. Additionally, a density functional theory (DFT) investigation explained the stability of the pesticide at pH 7 and the high reactivity of the pesticide in alkaline medium. The key nucleophilic reaction partner is hydroxyl ions instead of neutral water molecules. Furthermore, the calculated activation barrier for hydrolysis in alkaline medium is in agreement with the extrapolated and experimentally determined activation barrier at pH 14. AU - Chnirheb, A. AU - Harir, M. AU - Kanawati, B. AU - Fekete, A. AU - El Azzouzi, M.* AU - Hertkorn, N. AU - Schmitt-Kopplin, P. C1 - 3732 C2 - 28006 CY - Heidelberg SP - 2325-2334 TI - Hydrolysis of mefenpyrdiethyl: An analytical and DFT investigation. JO - Anal. Bioanal. Chem. VL - 398 IS - 5 PB - Springer PY - 2010 SN - 1618-2642 ER - TY - JOUR AB - One- and comprehensive two-dimensional gas chromatography were hyphenated with soft photoionization mass spectrometry. The characteristics of these two- and three-dimensional comprehensive separation techniques are discussed in detail. Using the innovative electron beam pumped excimer light source (EBEL) for single-photon ionization (SPI), organic molecules with ionization energies (E ( i )) of below 9.8 eV can be detected by a time-of-flight mass spectrometer (TOF-MS). SPI with 126 nm vacuum ultraviolet (VUV) photons enables the universal and soft ionization of organic molecules. SPI-TOF-MS hyphenated to one-dimensional gas chromatography results in a comprehensive two-dimensional separation method (GCxMS). To demonstrate this, diesel fuel was analyzed, and the resulting GCxMS chromatograms are discussed in depth. A three-dimensional separation method was also realized by combining comprehensive two-dimensional gas chromatography (GCxGC) with SPI-MS. In the resulting separation space, constituents originating from mineral oil diesel blended with biodiesel were dispersed along the two GC separation axes, while the molecular mass axis served as a third separation dimension. AU - Eschner, M.S. AU - Welthagen, W. AU - Gröger, T.M. AU - Gonin, M.* AU - Fuhrer, K.* AU - Zimmermann, R. C1 - 3116 C2 - 27958 SP - 1435-1445 TI - Comprehensive multidimensional separation methods by hyphenation of single-photon ionization time-of-flight mass spectrometry (SPI-TOF-MS) with GC and GCxGC. JO - Anal. Bioanal. Chem. VL - 398 IS - 3 PB - Springer PY - 2010 SN - 1618-2642 ER - TY - JOUR AB - This paper describes the combined set-up of on-line chemical analysis of gas phase by single-photon ionisation/resonance enhanced multiphoton ionisation-time-of-flight mass spectrometry (SPI/REMPI-TOFMS) and on-line particle size analysis by differential electrical mobility particle spectrometry (DMS 500) for the investigation of fresh cigarette mainstream smoke. SPI is well suited for the investigation of a great variety of organic species, whereas REMPI is highly sensitive for aromatic compounds. Gas phase measurements of filtered and unfiltered smoke are possible with the SPI/REMPI-TOFMS in order to determine the influence of the presence of particles on the chemical composition of the gas phase. Initial results are shown for the characterisation and comparison of three pure Virginia tobacco research cigarettes having filter ventilations of 0%, i.e. no filter ventilation, 35% and 70% ventilation. The three cigarette types are smoked under two different smoking regimes, a standard regime using puff parameters equivalent to the conventional International Standard Organisation regime and a more intense smoking regime. For the gas phase, qualitative puff-by-puff resolved yields of three selected compounds (acetaldehyde, phenol and styrene) are shown and compared. For particulate matter, particle number, count median diameter and total surface area are illustrated on a puff-by-puff basis. Yields of the chemicals analysed, puff number and surface area are in good agreement with the intensity of the smoking regime and the dilution of smoke by filter ventilation. However, gaseous compounds are influenced differently, depending whether an absolute particle filter is present or not, i.e. they can be totally removed (phenol), partially removed (styrene) or not affected (acetaldehyde). For particle analysis, the count median diameter decreases from puff to puff and is strongly dependent on the smoking regime and ventilation rate. Thereby, 0% ventilated cigarettes smoked under the intense regime result in the smallest count median diameters of ca. 180 nm, whereas 70% ventilated cigarettes smoked with a standard regime lead to the largest values of up to 280 nm. As particle diameter increases, particle number decreases as a consequence of increasing time for particle coagulation. AU - Adam, T. AU - McAughey, J.* AU - McGrath, C.* AU - Mocker, C. AU - Zimmermann, R. C1 - 825 C2 - 26253 CY - Heidelberg SP - 1193-1203 TI - Simultaneous on-line size and chemical analysis of gas phase and particulate phase of cigarette mainstream smoke. JO - Anal. Bioanal. Chem. VL - 394 IS - 4 PB - Springer PY - 2009 SN - 1618-2642 ER - TY - JOUR AB - A new immunosensor for the determination of procalcitonin was developed. A sandwich assay format was implemented on a polymethylmetacrylate optical biochip, opportunely shaped in order to obtain several flow channels and potentially suitable for point of care testing applications. The sandwich format makes use of two new rat monoclonal antibodies. The capture antibody was covalently immobilised on the surface of the plastic chip, and the detection antibody was labelled with DY647 dye. Different combinations of capture and detection antibodies were investigated, and particular attention was devoted in order to avoid the nonspecific adsorption. A limit of detection of 0.088 mg L-1 was achieved within the working range of 0.28-50 mg L-1 in buffer samples. The assay was also implemented in human serum, and 0.2 and 0.7-25 mg L-1 were the attained limit of detection and working range, respectively. AU - Baldini, F.* AU - Bolzoni, L.* AU - Giannetti, A.* AU - Keß, M. AU - Krämer, P. AU - Kremmer, E. AU - Porro, G.* AU - Senesi, F.* AU - Trono, C.* C1 - 1096 C2 - 26070 SP - 1183-1190 TI - A new procalcitonin optical immunosensor for POCT applications. JO - Anal. Bioanal. Chem. VL - 393 IS - 4 PB - Springer PY - 2009 SN - 1618-2642 ER - TY - JOUR AB - Sample preparation procedures are in most cases sample-and time-consuming and commonly require the use of a large amount of solvents. Automation in this regard can optimize the minimal-needed injection volume and the solvent consumption will be efficiently reduced. A new fully automated sample desalting and pre-concentration technique employing microextraction by packed sorbents (MEPS) cartridges is implemented and coupled to an ion cyclotron resonance Fourier-transform mass spectrometer (ICR-FT/MS). The performance of non-target mass spectrometric analysis is compared for the automated versus off-line sample preparation for several samples of aqueous natural organic matter. This approach can be generalized for any metabolite profiling or metabolome analysis of biological materials but was optimized herein using a well characterized but highly complex organic mixture: a surface water and its well-characterized natural organic matter and a marine sample having a highly salt charge and enabling to validate the presented automatic system for salty samples. The analysis of Suwannee River water showed selective C18-MEPS enrichment of chemical signatures with average H/C and O/C elemental ratios and loss of both highly polar and highly aromatic structures from the original sample. Automated on-line application to marine samples showed desalting and different chemical signatures from surface to bottom water. Relative comparison of structural footprints with the C18-concentration/desalting procedure however enabled to demonstrate that the surface water film was more concentrated in surface-active components of natural (fatty acids) and anthropogenic origin (sulfur-containing surfactants). Overall, the relative standard deviation distribution in terms of peak intensity was improved by automating the proposed on-line method. AU - Morales-Cid, G. AU - Gebefügi, I. AU - Kanawati, B. AU - Harir, M. AU - Hertkorn, N. AU - Rosselló-Mora, R.* AU - Schmitt-Kopplin, P. C1 - 2465 C2 - 26445 CY - Heidelberg SP - 797-807 TI - Automated microextraction sample preparation coupled on-line to FT-ICR-MS: Application to desalting and concentration of river and marine dissolved organic matter. JO - Anal. Bioanal. Chem. VL - 395 IS - 3 PB - Springer Heidelberg PY - 2009 SN - 1618-2642 ER - TY - JOUR AB - International Conferences on Trace Element Speciation organized at the Helmholtz Zentrum München provided an overview of the current status and performance of the multifaceted field of trace element speciation analysis. The conference emphasized the interdisciplinary character of speciation analysis and the large variety of the available techniques. An analysis on the environment and unprocessed food demonstrated arsenic speciation data for a whole marine ecosystem. Proposed approach was novel to elucidation of presently unknown biochemical pathways for formation of the large variety of arsenic species. Another session on food production and other industries presented the advancements on selenium speciation in food and food supplements and pointed out some of the remaining challenges in the field of speciation analysis. The analysis also examined the speciation and bioavailability of Zn and Cr in Zn-enriched and Cr-enriched yeast based food supplements. © Crown copyright in right of Canada 2008. AU - Nischwitz, V. AU - Michalke, B. C1 - 1328 C2 - 26053 SP - 415-418 TI - 4th international conference on trace element speciation in biomedical, nutritional and environmental sciences. JO - Anal. Bioanal. Chem. VL - 393 IS - 2 PB - Springer PY - 2009 SN - 1618-2642 ER - TY - JOUR AB - For the detection of security-relevant substances at low concentrations in complex matrices, coupling of thermal desorption-single photon ionization-ion trap mass spectrometry (TD-SPI-ITMS) was successfully tested. The main advantage of taking solid samples with a wipe pad followed by thermal desorption is the low detection limit by enhanced vapor pressure. Single photon ionization is a soft ionization technique which reduces the target ion fragmentation and shields bulk components with high ionization energies (IE) like nitrogen yielding to clearly arranged mass spectra with significant high mass peaks. To obtain low false-positive and false-negative rates, especially necessary for security-relevant substances, the ion trap mass spectrometer allows identification of signals with MS/MS studies. In this concept, the soft ionization technique fits well with the MS/MS studies, as peaks with high masses are generated yielding significant MS/MS fragments. For the ionization, photon energies between about 8 eV (155 nm) and 12 eV (103 nm) were generated with electron-beam-pumped rare gas excimer lamps (EBEL). Depending on the rare gas used, light with different photon energy is generated, adapted to the substances of interest. So, even most narcotics, having relatively low IEs, can be ionized with 8.4 eV photons without massive fragmentation. For most explosives, photons with higher energy must be used as their IEs are higher. In this work, a mobile setup with a commercial ion trap mass spectrometer has been developed and tested. Even a first real-scenario measurement campaign was accomplished successfully proving the field-suitability of the system. AU - Schramm, E. AU - Hölzer, J. AU - Pütz, M.* AU - Schulte-Ladbeck, R.* AU - Schultze, R.* AU - Sklorz, M.* AU - Ulrich, A.* AU - Wieser, J.* AU - Zimmermann, R. C1 - 5376 C2 - 27956 SP - 1795-1807 TI - Real-time trace detection of security-relevant compounds in complex sample matrices by thermal desorption-single photon ionization-ion trap mass spectrometry (TD-SPI-ITMS). JO - Anal. Bioanal. Chem. VL - 395 IS - 6 PB - Springer PY - 2009 SN - 1618-2642 ER - TY - JOUR AB - The development of selective and sensitive biological recognition elements, e.g., antibodies, for the detection of relevant blood markers is a great challenge in the field of biosensors. In this context, five new rat monoclonal antibodies (mAbs) for procalcitonin (PCT), a marker for bacterial infection and sepsis, were developed and characterized. One mAb, PROC1 3G3, was used as capture antibody. Four mAbs, PROC4 6C6, PROC4 6B2, PROC4 1G3, and PROC4 1D6, were used as detection mAbs, either as Protein G-purified or as biotinylated mAbs. A surface plasmon resonance (SPR) biosensor was used to characterize the antigen-antibody biomolecular interactions. The capture mAb (PROC1 3G3) has an equilibrium dissociation constant (K (D)) of 3.42 x 10(-8) M. All four detection mAbs (PROC4 6C6, PROC4 6B2, PROC4 1G3, and PROC4 1D6) are of high affinity (K (A) = 2.81-6.11 x 10(8) M(-1); K (D) = 1.64-3.56 x 10(-9) M) and have moderate dissociation rate constants (k (d) = 1.70-2.40 x 10(-3) s(-1)). Four different sandwich enzyme-linked immunosorbent assays (ELISAs) with standards of human recombinant (hr) PCT, using PROC1 3G3 as capture mAb and PROC4 mAbs as detection mAbs, respectively, led to highly specific determinations of PCT without cross-reactivities to calcitonin and katacalcin. The lower limits of quantification (LLOQ) for hrPCT (in 40 mM phosphate-buffered saline (PBS), pH 7.6) with these assays ranged from 2.3 to 12.8 microg L(-1). In addition, sandwich ELISAs were set up with biotinylated PROC4 mAbs, and with hrPCT in 4% human serum albumin (diluted 1:10 in 40 mM PBS, including 1:5 (v/v) LowCross Buffer(R)). The LLOQs of these sandwich assays ranged from 4.1 to 6.0 microg L(-1) and were thus much closer together for the different assays. With the latter assay setup (PROC1 3G3 as capture mAb, PROC4 6C6-biotin as detection mAb) a first collection of five serum samples was determined (healthy volunteers, unspiked, and spiked). Recovery rates for the spiked samples ranged from 98.3 to 115.7%. The newly developed anti-PCT mAbs should find broad applications in immunosensors for point-of-care diagnostics of sepsis and systemic inflammation processes. AU - Krämer, P.M. AU - Gouzy, M.-F. AU - Keß, M. AU - Kleinschmidt, U. AU - Kremmer, E. C1 - 465 C2 - 25641 SP - 727-736 TI - Development and characterization of new rat monoclonal antibodies for procalcitonin. JO - Anal. Bioanal. Chem. VL - 392 IS - 4 PB - Springer PY - 2008 SN - 1618-2642 ER - TY - JOUR AB - The development and characterization of one rat monoclonal antibody (mAb) for 2,4-dinitroaniline and of two rat mAbs for 2,6-dinitroaniline are described. With the immunization of rats with 2,4,6-trinitrophenyl-glycylglycine-keyhole limpet hemocyanine (KLH) conjugate one mAb (PK 5H6) has been developed and formatted into a competitive enzyme-linked immunosorbent assay (ELISA). This assay no. 1 is very sensitive for 2,4-dinitroaniline with a test midpoint of 0.24 +/- 0.06 mug L(-1) (n = 19) in 40 mM phosphate-buffered saline (PBS). A second hapten, 3-(4-amino-2,6-dinitrophenyl)propionic acid, which was also conjugated to KLH and used for the immunization of rats, led to two sensitive ELISAs for 2,6-dinitroaniline in 40 mM PBS with test midpoints of 0.61 +/- 0.08 mug L(-1) (n = 15; mAb DNT4 3C6; assay no. 2) and 0.94 +/- 0.29 mug L(-1) (n = 17; mAb DNT4 1A7, assay no. 3). Selectivities of all mAbs were checked with more than 20 compounds, including nitroaromatic compounds, 2,6-dinitroaniline pesticides, and other substituted derivatives of aniline. As very noticeable cross-reactivities, all mAbs recognize 2-chloro-4,6-dinitroaniline, 4-chloro-2,6-dinitroaniline and 2-bromo-4,6-dinitroaniline, the last of these being a major metabolite of the azo dye Disperse Blue 79. As first demonstrations of applications, two ELISAs (assays no. 1 and 2) were used for the analysis of 2,4- or 2,6-dinitroaniline in spiked water and soil samples. Recovery data were determined and the majority of these data were in the range of 90-120%. These assays can contribute to a very cost-effective and environmentally friendly immunochemical surveillance monitoring of environmental samples for contaminations with these compounds. To the best of the authors' knowledge, these are the first antibodies described for 2,4-dinitroaniline and for 2,6-dinitroaniline. AU - Krämer, P.M. AU - Forster, S. AU - Kremmer, E. C1 - 4525 C2 - 25356 SP - 1821-1835 TI - Enzyme-linked immunosorbent assays for the sensitive analysis of 2,4-dinitroaniline and 2,6-dinitroaniline in water and soil. JO - Anal. Bioanal. Chem. VL - 391 IS - 5 PB - Springer PY - 2008 SN - 1618-2642 ER - TY - JOUR AB - Recently we have established atmospheric-pressure laser ionisation (APLI) as a method for coupling time-of-flight mass spectrometric detectors (TOF MS) with chromatographic systems (HPLC and GC) to allow two-photon ionisation of non-polar aromatic compounds. Here we demonstrate that APLI can be combined with chip-electrospray ionisation (cESI) coupled to Fourier-transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) for ultrahigh-resolution analysis of complex samples. With the laser turned off, the analytes are ionised only by ESI, whereas when the laser is switched on non-polar aromatic substances also are ionised. In combination with the extremely high mass resolution of an FT-ICR MS, simultaneous qualitative analysis of polar and non-polar analytes is possible in both positive and negative modes, as is exemplified with a crude oil sample. Nevertheless, ion suppression was observed (up to ca. 70% for D(10)-pyrene) and thus sample preparation with chromatographic or electrophoretic pre-separation is necessary for quantitative analysis of targets. In addition, for the first time, the dopant-assisted APLI method in combination with cESI (DA-cESILI) was used for determination of 1-nitrocoronene. AU - Schmitt-Kopplin, P. AU - Englmann, M. AU - Rosselló-Mora, R.* AU - Schiewek, R.* AU - Brockmann, K.J.* AU - Benter, T.* AU - Schmitz, O.J.* C1 - 3312 C2 - 25709 SP - 2803-2809 TI - Combining chip-ESI with APLI (cESILI) as a multimode source for analysis of complex mixtures with ultrahigh-resolution mass spectrometry. JO - Anal. Bioanal. Chem. VL - 391 IS - 8 PB - Springer PY - 2008 SN - 1618-2642 ER - TY - JOUR AB - Soft single photon ionization (SPI)–time-of-flight mass spectrometry (TOFMS) is well suited for fast and comprehensive analysis of complex organic gas mixtures, which has been demonstrated in various applications. This work describes a calibration scheme for SPI, which enables quantification of a large number of compounds by only calibrating one compound of choice, in this case benzene. Photoionization cross sections of 22 substances were determined and related to the yield of benzene. These substances included six alkanes (pentane, hexane, heptane, octane, nonane, decane), three alkenes (propene, butane, pentene), two alkynes (propyne, butyne), two dienes (butadiene, isoprene), five monoaromatic species (benzene, toluene, xylene, styrene, monochlorobenzene) and NO. The cross sections of organic compounds differ by about one order of magnitude but the photoionization properties of compounds belonging to one compound class are rather similar. Therefore, the scheme can also be used for an approximate quantification of compound classes. This is demonstrated by a fast characterization and pattern recognition of two gasoline samples with different origins (Germany and South Africa) and a diesel sample (Germany). The on-line capability of the technique and the scheme is demonstrated by quantitatively monitoring and comparing the cold engine start of four vehicles: a gasoline passenger car, a diesel van, a motorbike and a two-stroke scooter. AU - Adam, T. AU - Zimmermann, R. C1 - 1262 C2 - 25308 SP - 1941-1951 TI - Determination of single photon ionization cross sections for quantitative analysis of complex organic mixtures. JO - Anal. Bioanal. Chem. VL - 389 IS - 6 PB - Springer PY - 2007 SN - 1618-2642 ER - TY - JOUR AB - Abstract Soft single-photon ionisation (SPI)–time-of-flight mass spectrometry (TOFMS) has been used to investigate the effect of different cigarette-lighting devices on the chemical composition of the mainstream smoke from the first cigarette puff. Lighting devices examined were a Borgwaldt electric lighter, a propane/butane gas lighter, a match, a candle, and the burning zone of another cigarette. To eliminate the effects of the different masses of tobacco burnt by use of the different lighting methods a normalisation procedure was performed which enabled investigation of changes in the chemical patterns of the resulting smoke. When another cigarette was used as the lighting device, elevated levels of ammonia and other nitrogen-containing substances were observed. These are high in the sidestream smoke of the cigarette used for lighting and would be drawn into the mainstream smoke of the cigarette being lit. In contrast, smoke from the cigarette lit by the electric lighter contained slightly higher normalised amounts of isoprene. Lighting the cigarette by use of a candle resulted in larger amounts of substances, e.g. benzene, which most probably originated from thermal decomposition of wax. The composition of the first puff of smoke obtained by use of the three lighting methods with open flames (gas lighter, match, and candle) was usually similar whereas the composition of the smoke produced by use of the electric lighter and the cigarette as the lighter were more unique. The chemical patterns generated by the different lighting devices could, however, be separated by principal-component analyses. Two additional test series were also studied. In the first the cigarette was lit with an electric lighter, then extinguished, the ash was cut off, and the cigarette was re-lit. In the second the cigarette was heated in an oven to 80 °C for 5 min before being lit. These treatments did not result in changes in the chemical composition compared with cigarettes lit in the ordinary way. AU - Adam, T.* AU - Baker, R.R.* AU - Zimmermann, R. C1 - 3914 C2 - 24309 SP - 575-584 TI - Investigation, by single photon ionisation (SPI)-time-of-flight mass spectrometry (TOFMS), of the effect of different cigarette-lighting devices on the chemical composition of the first cigarette puff. JO - Anal. Bioanal. Chem. VL - 387 IS - 2 PB - Springer PY - 2007 SN - 1618-2642 ER - TY - JOUR AB - One third of all genes of various organisms encode membrane proteins, emphasizing their crucial cellular role. However, due to their high hydrophobicity, membrane proteins demonstrate low solubility and a high tendency for aggregation. Indeed, conventional two-dimensional gel electrophoresis (2-DE), a powerful electrophoretic method for the separation of complex protein samples that applies isoelectric focusing (IEF) in the first dimension and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) in the second dimension, has a strong bias against membrane proteins. This review describes two-dimensional electrophoretic techniques that can be used to separate membrane proteins. Alternative methods for performing conventional 2-DE are highlighted; these involve replacing the IEF with electrophoresis using cationic detergents, namely 16-benzyldimethyl-n-hexadecylammonium chloride (16-BAC) and cetyl trimethyl ammonium bromide (CTAB), or the anionic detergent SDS. Finally, the separation of native membrane protein complexes through the application of blue and clear native gel electrophoresis (BN/CN-PAGE) is reviewed, as well as the free-flow electrophoresis (FFE) of membranes. AU - Braun, R.J. AU - Kinkl, N. AU - Beer, M. AU - Ueffing, M. C1 - 4315 C2 - 24598 SP - 1033-1045 TI - Two-dimensional electrophoresis of membrane proteins. JO - Anal. Bioanal. Chem. VL - 389 IS - 4 PB - Springer PY - 2007 SN - 1618-2642 ER - TY - JOUR AB - A commercially available piezo-driven drop-on-demand dispenser was tested for its suitability for the preparation of analytical calibration standards and in a standard addition approach prior to quantitative ultra performance liquid chromatography (UPLC) analysis of homoserines. The reproducibility of the drop-on-demand dosing system was tested and the verification of the droplet volume was performed by preparing a series of 1.0 mg/L caffeine standard solutions from a 1,000.0 mg/L stock solution and analysis of the concentrations obtained by UPLC. The reproducibility was better than 1% relative standard deviation from measurement to measurement and the highest was 1.6% from day to day. The results were compared with the conventional way of generating standard solutions (pipetting). A gravimetric method and a photography-based method for the determination of the average single droplet volume were compared and found to be in very good agreement. The system was employed for the quantification of N-decanoyl homoserine by standard addition in bacterial culture supernatants containing this analyte. The agreement with conventional quantification techniques was high. The paper shows the feasibility of the approach with advantages in low sample and solvent volume consumption and very good reproducibility and reliability combined with easy usage. AU - Englmann, M. AU - Fekete, A. AU - Gebefügi, I. AU - Schmitt-Kopplin, P. C1 - 170 C2 - 24529 SP - 1109-1116 TI - The dosage of small volumes for chromatographic quantifications using a drop-on-demand dispenser system. JO - Anal. Bioanal. Chem. VL - 388 IS - 5-6 PB - Springer PY - 2007 SN - 1618-2642 ER - TY - JOUR AB - N-Acylated homoserine lactones (AHLs) are produced by Gram-negative bacteria as communication signals and are frequently studied as mediators of the “quorum sensing” response of bacterial communities. Several reports have recently been published on the identification of AHLs from different species and attempts have been made to study their role in natural habitats, for example the surface of plant roots in the rhizosphere. In this article, different analytical methods, including bacterial biosensors and chromatographic techniques, are reviewed. A concept for assignment of the structures of AHLs is also presented. The retention behaviour of derivatives of AHLs containing ?-keto or hydroxyl groups and/or double bonds has been evaluated in relation to the separation behaviour of AHLs with saturated and unsubstituted alkanoyl chains. Samples have also been analysed by high resolution mass spectrometry (Fourier-transform ion-cyclotron-resonance mass spectrometry, FTICR-MS), nano liquid chromatography–electrospray ionization ion trap mass spectrometry (nano-LC–MS) and by the aid of a biosensor. The results obtained from ultra performance liquid chromatography (UPLC), FTICR-MS, nano-LC–MS, and bioassays have been compared to attempt structural characterisation of AHL without chemical synthesis of analytical standards. The method was used to identify the major AHL compound produced by the rhizosphere bacterium Acidovorax sp. N35 as N-(3-hydroxydecanoyl)homoserine lactone. AU - Fekete, A. AU - Frommberger, M. AU - Rothballer, M. AU - Li, X. AU - Englmann, M. AU - Fekete, J.* AU - Hartmann, A. AU - Eberl, L.* AU - Schmitt-Kopplin, P. C1 - 3936 C2 - 24468 SP - 455-465 TI - Identification of bacterial N-acylhomoserine lactones (AHLs) with a combination of ultra-performance liquid chromatography (UPLC), ultra-high-resolution mass spectrometry, and in-situ biosensors. JO - Anal. Bioanal. Chem. VL - 387 IS - 2 PB - Springer PY - 2007 SN - 1618-2642 ER - TY - JOUR AB - Bacterial intraspecies and interspecies communication in the rhizosphere is mediated by diffusible signal molecules. Many Gram-negative bacteria use N-acyl-homoserine lactones (AHLs) as autoinducers in the quorum sensing response. While bacterial signalling is well described, the fate of AHLs in contact with plants is much less known. Thus, adsorption, uptake and translocation of N-hexanoyl- (C6-HSL), N-octanoyl- (C8-HSL) and N-decanoyl-homoserine lactone (C10-HSL) were studied in axenic systems with barley (Hordeum vulgare L.) and the legume yam bean (Pachyrhizus erosus (L.) Urban) as model plants using ultra-performance liquid chromatography (UPLC), Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and tritium-labelled AHLs. Decreases in AHL concentration due to abiotic adsorption or degradation were tolerable under the experimental conditions. The presence of plants enhanced AHL decline in media depending on the compounds’ lipophilicity, whereby the legume caused stronger AHL decrease than barley. All tested AHLs were traceable in root extracts of both plants. While all AHLs except C10-HSL were detectable in barley shoots, only C6-HSL was found in shoots of yam bean. Furthermore, tritium-labelled AHLs were used to determine short-term uptake kinetics. Chiral separation by GC-MS revealed that both plants discriminated D-AHL stereoisomers to different extents. These results indicate substantial differences in uptake and degradation of different AHLs in the plants tested. AU - Götz, C. AU - Fekete, A. AU - Gebefügi, I.L. AU - Forczek, S.T.* AU - Fuksová, K.* AU - Li, X. AU - Englmann, M. AU - Gryndler, M.* AU - Hartmann, A. AU - Matucha, M.* AU - Schmitt-Kopplin, P. AU - Schröder, P. C1 - 4521 C2 - 24714 SP - 1447-1457 TI - Uptake, degradation and chiral discrimination of N-acyl-D/L-homoserine lactones by barley (Hordeum vulgare) and yam bean (Pachyrhizus erosus) plants. JO - Anal. Bioanal. Chem. VL - 389 IS - 5 PB - Springer PY - 2007 SN - 1618-2642 ER - TY - JOUR AB - The photodecomposition of imazamox, a herbicide of the imidazolinone family, was investigated in pure water. The main photoproducts from the photolysis were followed over time by liquid chromatography mass spectrometry and structures were proposed from exact mass determinations obtained by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. The method comprised exact mass determination with better than 0.2 ppm mass accuracy and a corresponding structural visualization taking care of respective isotopes with an adapted van Krevelen diagram that enabled a systematic approach to the characterisation of the elementary composition of each photoproduct. By taking advantage of the high resolving power of FT-ICR MS to make precise formula assignments, the derived 2D van Krevelen diagram (O/C; H/C; m/z) enabled one to structurally differentiate the formed photoproducts and to propose a degradation pathway for imazamox. AU - Harir, M. AU - Frommberger, M. AU - Gáspár, A. AU - Martens, D.* AU - Kettrup, A. AU - El Azzouzi, M.* AU - Schmitt-Kopplin, P. C1 - 677 C2 - 24844 SP - 1459-1467 TI - Characterization of imazamox degradation by-products by using liquid chromatography mass spectrometry and high-resolution Fourier transform ion cyclotron resonance mass spectrometry. JO - Anal. Bioanal. Chem. VL - 389 IS - 5 PB - Springer PY - 2007 SN - 1618-2642 ER - TY - JOUR AB - This perspective article provides an assessment of the state-of-the-art in the molecular-resolution analysis of complex organic materials. These materials can be divided into biomolecules in complex mixtures (which are amenable to successful separation into unambiguously defined molecular fractions) and complex nonrepetitive materials (which cannot be purified in the conventional sense because they are even more intricate). Molecular-level analyses of these complex systems critically depend on the integrated use of high-performance separation, high-resolution organic structural spectroscopy and mathematical data treatment. At present, only high-precision frequency-derived data exhibit sufficient resolution to overcome the otherwise common and detrimental effects of intrinsic averaging, which deteriorate spectral resolution to the degree of bulk-level rather than molecular-resolution analysis. High-precision frequency measurements are integral to the two most influential organic structural spectroscopic methods for the investigation of complex materials-NMR spectroscopy (which provides unsurpassed detail on close-range molecular order) and FTICR mass spectrometry (which provides unrivalled resolution)-and they can be translated into isotope-specific molecular-resolution data of unprecedented significance and richness. The quality of this standalone de novo molecular-level resolution data is of unparalleled mechanistic relevance and is sufficient to fundamentally advance our understanding of the structures and functions of complex biomolecular mixtures and nonrepetitive complex materials, such as natural organic matter (NOM), aerosols, and soil, plant and microbial extracts, all of which are currently poorly amenable to meaningful target analysis. The discrete analytical volumetric pixel space that is presently available to describe complex systems (defined by NMR, FT mass spectrometry and separation technologies) is in the range of 10(8-14) voxels, and is therefore capable of providing the necessary detail for a meaningful molecular-level analysis of very complex mixtures. Nonrepetitive complex materials exhibit mass spectral signatures in which the signal intensity often follows the number of chemically feasible isomers. This suggests that even the most strongly resolved FTICR mass spectra of complex materials represent simplified (e.g. isomer-filtered) projections of structural space. AU - Hertkorn, N. AU - Ruecker, C.* AU - Meringer, M.* AU - Gugisch, R.* AU - Frommberger, M. AU - Perdue, E.M. AU - Witt, M. AU - Schmitt-Kopplin, P. C1 - 1728 C2 - 24898 SP - 1311-1327 TI - High-precision frequency measurements: Indispensable tools at the core of the molecular-level analysis of complex systems. JO - Anal. Bioanal. Chem. VL - 389 IS - 5 PB - Springer PY - 2007 SN - 1618-2642 ER - TY - JOUR AB - Immunochemical methods (in particular immunoassays) have been applied to spring and surface water samples, respectively, which were set-up as reference materials (RM) within two proficiency testing campaigns. For the first set of proficiency tests (PTs) described here (which were actually the second round of PTs organized, spring 2005), three ELISAs (enzyme-linked immunosorbent assays) were employed in the enzyme tracer format for isoproturon, diuron, and atrazine, respectively. Results were evaluated in comparison with conventional reference methods (LC, GC). Based on their Z-score laboratory performances, the results for isoproturon and diuron were satisfactory, both for fortified spring water and for the blind solution. The results for atrazine were strongly influenced by other triazines present and needed detailed interpretation. For the second set of PTs described here (which were actually the third round of PTs organized, spring 2006), two ELISAs in the coating antigen format were used for isoproturon and diuron, and the result was included with the results obtained by conventional methods during the PTs. The results (the Z-scores) for isoproturon were again classified as satisfactory, in both fortified surface water and blind solution. The results for diuron in ELISA showed an influence of the water matrix, while the analysis of the blind solution was satisfactory. In addition, an ELISA in the enzyme tracer format was applied to analyze isoproturon, diuron, and atrazine in surface water samples, which had been set-up and spiked during a field trial (tank experiment) at the Maas River at Eijsden, The Netherlands. The immunoassay results were compared with those from an in-house on-line SPE LC/MS–MS used as reference. Although the immunochemical results were sometimes higher than those determined in the reference analysis, the general concentration trends in the samples were similar. The contribution of immunochemical methods to the implementation of the European Water Framework Directive is also discussed. AU - Krämer, P.M. AU - Martens, D.* AU - Forster, S. AU - Ipolyi, I.* AU - Brunori, C.* AU - Morabito, R.* C1 - 2843 C2 - 24316 SP - 1435-1448 TI - How can immunochemical methods contribute to the implementation of the water framework directive? JO - Anal. Bioanal. Chem. VL - 387 IS - 4 PB - Springer PY - 2007 SN - 1618-2642 ER - TY - JOUR AB - Since highly sensitive on-line coupling of UPLC with FTICR-MS is technically infeasible due to their different scan rates, at-line coupling of these techniques was developed for rapid analysis. To enable cutting of one peak of the chromatogram into one fraction, several conditions and relationships were investigated, e.g. the optimum volume of the inserted delay loop, the relationship between retention time, loop outlet drop speed, individual drop volume versus mobile phase composition under constant speed, and linear solvent strength gradient elution modes. Good and reproducible results were achieved applying UPLC as an efficient separation and fast fractionation tool before the FTICR-MS measurements. A chip-based nanoelectrospray ionization system was employed which was perfectly suited to handling the small-volume fractions and was thus chosen for the at-line coupling. The method was initially applied to spiked extracts of cell-free bacterial culture supernatants in which bacterial signalling compounds, namely N-acyl homoserine lactones (AHL), were detected. Good reproducibility and high recovery was observed. Afterwards, a culture supernatant of Erwinia sp. JX3.2, a putative AHL producer, was investigated and N-hexanoyl-homoserine lactone was determined as a possible signalling molecule. More reliable assignments were achieved by use of at-line coupling of UPLC and FTICR-MS compared with off-line measurements. AU - Li, X. AU - Fekete, A. AU - Englmann, M. AU - Frommberger, M. AU - Lv, S.* AU - Chen, G.* AU - Schmitt-Kopplin, P. C1 - 673 C2 - 24843 SP - 1439-1446 TI - At-line coupling of UPLC to chip-electrospray-FTICR-MS. JO - Anal. Bioanal. Chem. VL - 389 IS - 5 PB - Springer PY - 2007 SN - 1618-2642 ER - TY - JOUR AU - Schmitt-Kopplin, P. AU - Hertkorn, N. C1 - 4524 C2 - 24961 SP - 1309-1310 TI - Ultrahigh resolution mass spectrometry. JO - Anal. Bioanal. Chem. VL - 389 IS - 5 PB - Springer PY - 2007 SN - 1618-2642 ER - TY - JOUR AB - On-line analysis of trace and bulk gas compounds in the burning chamber of a waste-incineration plant has been performed, with high temporal resolution, by use of a variety of distinctly different measurement techniques. Time-of-flight mass spectrometry was performed with simultaneous use of three ionization techniques-resonance-enhanced multiphoton ionization (REMPI), single-photon ionization (SPI), and electron-impact ionization (EI). Chemical-ionization mass spectrometry (CIMS), Fourier-transform infrared spectrometry (FTIR), and electrochemical methods were also used. Sampling was conducted by means of a newly developed air-cooled stainless steel lance, to cope with the high temperatures and elevated particle concentrations at the sampling location. Nitrogen species were mainly nitrogen monoxide, ammonia, and hydrogen cyanide (HCN), with a small amount (approximately 0.3%) of aromatic nitrogen compounds. NO, NH(3), and HCN are the main contributors to the NO(x)-formation process in the postulated fuel-NO reaction scheme dominant at this location. The NO recycling process thereby plays a major role. Changes in plant operating conditions have a noticeable impact only when the air supply is varied. For example, reduction of oxygen leads to an increase in the HCN fraction of the total nitrogen content and a decrease in the NO fraction, and vice versa AU - Streibel, T. AU - Hafner, K. AU - Mühlberger, F. AU - Adam, T. AU - Warnecke, R.* AU - Zimmermann, R. C1 - 1704 C2 - 23503 SP - 1096-1106 TI - Investigation of NOx precursor compounds and other combustion by-products in the primary combustion zone of a waste-incineration plant using on-line, real-time mass spectrometry and Fourier-transform infrared spectrometry (FTIR). JO - Anal. Bioanal. Chem. VL - 384 IS - 5 PY - 2006 SN - 1618-2642 ER - TY - JOUR AU - Adam, T. AU - Ferge, T. AU - Mitschke, S. AU - Streibel, T. AU - Baker, R.R.* AU - Zimmermann, R. C1 - 3917 C2 - 22666 SP - 487-499 TI - Discrimination of three tobacco types (Burley, Virginia and Oriental) by pyrolysis single-photon ionisation-time-of-flight mass spectrometry and advanced statistical methods. JO - Anal. Bioanal. Chem. VL - 381 PY - 2005 SN - 1618-2642 ER - TY - JOUR AU - Krämer, P.M. AU - Kremmer, E. AU - Weber, C.M.* AU - Ciumasu, I.M.* AU - Forster, S. AU - Kettrup, A. C1 - 144 C2 - 22826 SP - 1919-1933 TI - Development of new rat monoclonal antibodies with different selectivities and sensitivities for 2,4,6-trinitrotoluene (TNT) and other nitroaromatic compounds. JO - Anal. Bioanal. Chem. VL - 382 PY - 2005 SN - 1618-2642 ER - TY - JOUR AU - Lintelmann, J. AU - Fischer, K. AU - Karg, E.W. AU - Schröppel, A. C1 - 1507 C2 - 22494 SP - 508-519 TI - Determination of selected polycyclic aromatic hydrocarbons and oxygenated polycyclic aromatic hydrocarbons in aerosol samples by high-performance liquid chromatography and liquid chromatography-tandem mass spectrometry. JO - Anal. Bioanal. Chem. VL - 381 PY - 2005 SN - 1618-2642 ER - TY - JOUR AU - Michalke, B. AU - Schramel, P. C1 - 2786 C2 - 22614 SP - 394-396 TI - Third international conference on trace element speciation in biomedical, nutritional and environmental sciences. JO - Anal. Bioanal. Chem. VL - 381 PY - 2005 SN - 1618-2642 ER - TY - JOUR AU - Sutthivaiyakit, P.* AU - Achatz, S. AU - Lintelmann, J. AU - Aungpradit, T.* AU - Chanwirat, R.* AU - Chumanee, S.* AU - Kettrup, A. C1 - 2024 C2 - 22554 SP - 268-276 TI - LC-MS/MS method for the confirmatory determination of aromatic amines and its application in textile analysis. JO - Anal. Bioanal. Chem. VL - 381 PY - 2005 SN - 1618-2642 ER - TY - JOUR AU - Wang, J.* AU - Xie, P.* AU - Kettrup, A. AU - Schramm, K.-W.* C1 - 3704 C2 - 23219 SP - 1609-1618 TI - Evaluation of soot particles of biomass fuels with endocrine-modulating activity in yeast-based bioassay. JO - Anal. Bioanal. Chem. VL - 381 PY - 2005 SN - 1618-2642 ER - TY - JOUR AU - Wittmaack, K. C1 - 3083 C2 - 23053 SP - 702-712 TI - Concept and validation of a novel approach for producing large batches of reference material of ambient aerosols on filters. JO - Anal. Bioanal. Chem. VL - 381 PY - 2005 SN - 1618-2642 ER - TY - JOUR AU - Zimmermann, R. C1 - 3589 C2 - 22488 SP - 57-60 TI - Laser ionisation mass spectrometry for on-line analysis of complex gas mixtures and combustion effluents. JO - Anal. Bioanal. Chem. VL - 381 PY - 2005 SN - 1618-2642 ER - TY - JOUR AB - A simple method for the simultaneous, rapid and sensitive determination of N-acylhomoserine lactone signaling molecules in bacterial isolates, without prior sample preconcentration and with minimal sample cleanup, is presented. The analysis relies on the combination of analyte preconcentration and separation on a single device: a relatively large sample volume (1-5 muL) is directly loaded onto a laboratory-made, miniaturized (75 mum i.d.) reverse phase nano-liquid chromatography column, connected on-line to a microelectrospray-ionization ion trap mass spectrometer. In a first step the analyte is adsorbed (and so concentrated) at the beginning of the column, and is eluted and selectively separated in a second step by the organic mobile phase. Sample preconcentration follows the mechanisms of solid phase extraction on a nano-scale, while separation takes place according to classical liquid chromatography separation principles. The columns can be manufactured easily, are simply connected, and used with minimal solvent amounts; this makes this method extremely robust and cost-effective. The analytical setup was found to be routinely quantitative down to a concentration of 10 ng/mL (corresponding to a total analyte amount of 10 pg or ca. 50 fmol). The limit of detection was reached at 1 ng/mL (1 pg, ca. 5 fmol). Compared to the classical AHL analysis of bacterial cultures with biosensors, where selectivity and sensitivity is often limited, this rapid analytical technique is a substantial qualitative and quantitative improvement. Two unsubstituted N-acylhomoserine lactones could be identified and quantified from a Burkholderia cepacia culture supernatant in a chloroform extract. AU - Frommberger, M. AU - Schmitt-Kopplin, P. AU - Ping, G.* AU - Frisch, H. AU - Schmid, M. AU - Zhang, Y.* AU - Hartmann, A. AU - Kettrup, A. C1 - 1560 C2 - 21773 SP - 1014-1020 TI - A simple and robust set-up for on-column sample preconcentration - nano-liquid chromatography - electrospray ionization mass spectrometry for the analysis of N-acylhomoserine lactones. JO - Anal. Bioanal. Chem. VL - 378 IS - 4 PY - 2004 SN - 1618-2642 ER - TY - JOUR AB - The effects of 17 alpha-ethinylestradiol (EE), an endocrine disruptor, on zoo- and phytoplankton were studied in outdoor 230-L still-water microcosms. Cell density and biomass, diversity, and community composition were analyzed. Five microcosms were treated by controlled release for six weeks, three by direct application of EE. To investigate recovery, sampling was continued for four weeks after treatment. Most characteristics of the zooplankton were not unambiguously affected by EE. Only the relative density of copepods, especially of their larvae, decreased significantly after EE application. For phytoplankton, no unambiguous concentration- or toxodose-correlated effects on any biotic characteristics could be found. However, most properties of the phytoplankton deviated from those of controls, i.e. tended to be smaller (number of species per microcosm, biomass, cell density) or covered a wider range (diversity, evenness). PCA indicated a shift of species structure in the treated microcosms. This was supported by the species scores calculated by the principal response curve method, although the principal response curve itself showed no clear EE-correlated shifts. High variability within the biocenosis between microcosms and over time, probably because of disturbance of the ecosystem before starting of the test, might have superimposed EE-dependent effects. AU - Hense, B.A. AU - Severin, G.F. AU - Welzl, G. AU - Schramm, K.-W. C1 - 1244 C2 - 21690 SP - 716-724 TI - Effects of 17alpha-ethinylestradiol on zoo- and phytoplankton in lentic microcosms. JO - Anal. Bioanal. Chem. VL - 378 IS - 3 PB - Springer PY - 2004 SN - 1618-2642 ER - TY - JOUR AB - Compound-specific stable isotope analysis (CSIA) using gas chromatography-isotope ratio mass spectrometry (GC/IRMS) has developed into a mature analytical method in many application areas over the last decade. This is in particular true for carbon isotope analysis, whereas measurements of the other elements amenable to CSIA (hydrogen, nitrogen, oxygen) are much less routine. In environmental sciences, successful applications to date include (i) the allocation of contaminant sources on a local, regional, and global scale, (ii) the identification and quantification of (bio)transformation reactions on scales ranging from batch experiments to contaminated field sites, and (iii) the characterization of elementary reaction mechanisms that govern product formation. These three application areas are discussed in detail. The investigated spectrum of compounds comprises mainly n-alkanes, monoaromatics such as benzene and toluene, methyl tert-butyl ether (MTBE), polycyclic aromatic hydrocarbons (PAHs), and chlorinated hydrocarbons such as tetrachloromethane, trichloroethylene, and polychlorinated biphenyls (PCBs). Future research directions are primarily set by the state of the art in analytical instrumentation and method development. Approaches to utilize HPLC separation in CSIA, the enhancement of sensitivity of CSIA to allow field investigations in the mug L-1 range, and the development of methods for CSIA of other elements are reviewed. Furthermore, an alternative scheme to evaluate isotope data is outlined that would enable estimates of position-specific kinetic isotope effects and, thus, allow one to extract mechanistic chemical and biochemical information. AU - Schmidt, T.C.* AU - Zwank, L.* AU - Elsner, M.* AU - Berg, M.* AU - Meckenstock, R.U. AU - Haderlein, S.B.* C1 - 4949 C2 - 21717 SP - 283-300 TI - Compound-specific stable isotope analysis of organic contaminants in natural environments: A critical review of the state of the art, prospects and future challenges. JO - Anal. Bioanal. Chem. VL - 378 IS - 2 PY - 2004 SN - 1618-2642 ER - TY - JOUR AU - Voigt, K. AU - Brüggemann, R.* AU - Pudenz, S.* C1 - 3940 C2 - 22095 SP - 467-474 TI - Chemical databases evaluated by order theoretical tools. JO - Anal. Bioanal. Chem. VL - 380 PY - 2004 SN - 1618-2642 ER - TY - JOUR AU - Bianco, G.* AU - Schmitt-Kopplin, P. AU - Crescenzi, A.* AU - Comes, S.* AU - Kettrup, A. AU - Cataldi, T.R.I.* C1 - 9731 C2 - 20927 SP - 799-804 TI - Evaluation of glycoalkaloids in tubers of genetically modified virus Y-resistant potato plants (var. Desiree) by non-aqueous capillary electrophoresis coupled with electrospray ionization mass spectrometry (NACE-ESI-MS). JO - Anal. Bioanal. Chem. VL - 375 PY - 2003 SN - 1618-2642 ER - TY - JOUR AU - Nischwitz, V. AU - Michalke, B. AU - Kettrup, A. C1 - 9729 C2 - 20843 SP - 145-156 TI - Identification and qualification of metallothionein isoforms and superoxide dismutase in spiked liver extracts using HPLC-ESI-MS offline coupling and HPLC-ICP-MS online coupling. JO - Anal. Bioanal. Chem. VL - 375 PY - 2003 SN - 1618-2642 ER - TY - JOUR AU - Martens, D.* AU - Gfrerer, M.* AU - Wenzl, Th.* AU - Zhang, A.* AU - Gawlik, B.M.* AU - Schramm, K.-W. AU - Lankmayr, E.* AU - Kettrup, A. C1 - 9730 C2 - 20644 SP - 562-568 TI - Comparison of different extraction techniques for the determination of polychlorinated organic compounds in sediment. JO - Anal. Bioanal. Chem. VL - 372 PY - 2002 SN - 1618-2642 ER - TY - JOUR AB - Investigations are described to extract Se-species from a bacterial sample. The five extraction methods investigated were: hot water, protease, lysozyme, lysozyme-protease, and HCl hydrolysis. The extraction efficiency was determined by comparing the total amounts of selenium in the sample after pressure digestion with the amounts extracted by the different methods described. Efficiencies were found to be only 1% (hot water), ca. 8% (protease, HCl hydrolysis) or ca. 12% (lysozyme, lysozyme-protease). The Se-peak patterns were compared after investigating the extracts with strong anion exchange chromatography-inductively coupled plasma mass spectrometry (SAX-ICP-MS). Most promising were the lysozyme-assisted procedures, which showed the highest diversity of species. Here, in the protease-lysozyme approach, the protease seemed to break down species that had been extracted by lysozyme from the bacterial wall (murein sacculus). The other approaches seemed not to extract many species. Hot water extraction was completely unsuitable, extracting only low amounts of a single, unknown species. AU - Michalke, B. AU - Witte, H. AU - Schramel, P. C1 - 10379 C2 - 20036 SP - 444-447 TI - Effect of different extraction procedures on the yield and pattern of Se-species in bacterial samples. JO - Anal. Bioanal. Chem. VL - 372 IS - 3 PB - Springer PY - 2002 SN - 1618-2642 ER - TY - JOUR AU - Michalke, B. AU - Schramel, P. C1 - 22039 C2 - 20641 SP - 506 S. TI - Trace Element Speciation in Biological and Environmental Sciences. JO - Anal. Bioanal. Chem. VL - 372 (Special Issue) PY - 2002 SN - 1618-2642 ER - TY - JOUR AB - Recently a new approach for the analysis of iodinated organic species in human serum has been developed using liquid chromatography-inductively coupled plasma-mass spectrometry (LC-ICP-MS). This method enables quantification of iodide, T4 and T3, as well as reverse T3 (rT3) and the synthetic precursors of TH, monoiodotyrosine (MIT), and diiodotyrosine (DIT) in a single injection. In this work, the LC-ICP-MS approach was used to analyze whole-body homogenates of adult male and female zebrafish (Danio rerio) and tadpoles of the African clawed frog (Xenopus laevis) at two different developmental stages (NF58 and 61) according to Nieuwkoop and Faber. The data demonstrate that the LC-ICP-MS method was successful at measuring I-, MIT, DIT, T4, T3, and rT3 in these two species. Furthermore, the method also detected five additional iodinated compounds which are currently unidentified. AU - Simon, R. AU - Tietge, J.E.* AU - Michalke, B. AU - Degitz, S.* AU - Schramm, K.-W. C1 - 10380 C2 - 20035 SP - 481-485 TI - Iodine species and the endocrine system :Thyroid hormone levels in adult Danio rerio and developing Xenopus laevis. JO - Anal. Bioanal. Chem. VL - 372 IS - 3 PB - Springer PY - 2002 SN - 1618-2642 ER -