TY  - JOUR
AB  - The development of orthogonal acceleration time-of-flight (oa-tof) technology is driven forward due to higher mass accuracy and resolving power than conventional linear/reflectron tof instruments. This is achieved with a more accurate definition of starting energies and coordinates of ions by spatial separation of ion generation and orthogonal ion extraction. Consequently, the ability to cover the whole mass spectral range without scanning is not given anymore. Therefore, continuous ion sources are favored for ensuring high duty cycles and thus high temporal resolution. For pulsed ion sources, high repetition rates are mandatory for covering large m/z ranges without losing their high temporal resolution. We have combined an oa-tof with deuterium lamp single-photon ionization (SPI) as a continuous ion source together with a pulsed 2000 Hz excimer (KrF) laser for resonance enhanced multi-photon ionization (REMPI). These two ionization techniques can be used simultaneously. To the best of our knowledge, this system is the first of its kind in combining a vacuum pulsed ionization source with an oa-tof instrument without any other ion storage hardware. The combination of a soft broadband ionization for organics (SPI) in combination with a very sensitive and selective soft ionization (REMPI) can be used for covering the whole mass range or in targeted on-line monitoring cases one or several smaller mass ranges. To demonstrate the simultaneous SPI/REMPI-oa-tof technique, two applicative areas are explored: on-line monitoring of coffee roast gas emissions and e-cigarette vapor. The complementary information from SPI and REMPI signals are combined in a way to exploit the advantages of both ionization types. In a further development step, a second data acquisition card is built into the system. This modification allows the independent storage of data from both ionization methods without mixing. For demonstration, a third example with a GC measurement is provided. The last example shows the possibility of modified sensitivities for different mass regions in REMPI data acquisition without affecting the SPI channel. The newly developed system shows high robustness in terms of measurements in real industrial environments. The simultaneous measurement technique provides a higher density of information in a single measurement, saving time and resources.
AU  - Heide, J.*
AU  - Ehlert, S.*
AU  - Koziorowski, T.*
AU  - Rüger, C.P.*
AU  - Walte, A.*
AU  - Zimmermann, R.
C1  - 65801
C2  - 52912
SP  - 3662-3674
TI  - Simultaneous on-line vacuum single- and multi-photon ionization on an orthogonal acceleration time-of-flight mass spectrometer platform.
JO  - Analyst
VL  - 147
IS  - 16
PY  - 2022
SN  - 0003-2654
ER  - 

TY  - JOUR
AB  - We developed a novel fast gas chromatography (fastGC) instrument with integrated sampling of volatile organic compounds (VOCs) and detection by single-photon ionisation (SPI) time-of-flight mass spectrometry (TOFMS). A consumable-free electrical modulator rapidly cools down to -55 °C to trap VOCs and inject them on a short chromatographic column by prompt heating to 300 °C, followed by carrier gas exchange from air to helium. Due to the low thermal mass and optical heating, the fastGC is operated within total runtimes including cooling for 30 s and 15 s, referring to hyper-fast GC, and at a constantly increasing temperature ramp from 30 °C to 280 °C. The application of soft SPI-TOFMS allows the detection of co-eluting VOCs of different molecular compositions, which cannot be resolved by conventional GC (cGC) with electron ionisation (EI). Among other analytical figures of merit, we achieved limits of detection for toluene and p-xylene of 2 ppb and 0.5 ppb, respectively, at a signal-to-noise ratio of 3 and a linear response over a range of more than five orders of magnitude. Furthermore, we demonstrate the performance of the instrument on samples from the fields of environmental research and food science by headspace analysis of roasted coffee beans and needles from coniferous trees as well as by quasi-real-time analysis of biomass burning emissions and coffee roast gas.
AU  - Gehm, C.*
AU  - Schnepel, K.*
AU  - Czech, H.
AU  - Miersch, T.*
AU  - Ehlert, S.*
AU  - Zimmermann, R.
C1  - 61941
C2  - 50523
CY  - Thomas Graham House, Science Park, Milton Rd, Cambridge Cb4 0wf, Cambs, England
SP  - 3137-3149
TI  - Hyper-fast gas chromatography and single-photon ionisation time-of-flight mass spectrometry with integrated electrical modulator-based sampling for headspace and online VOC analyses.
JO  - Analyst
VL  - 146
IS  - 10
PB  - Royal Soc Chemistry
PY  - 2021
SN  - 0003-2654
ER  - 

TY  - JOUR
AB  - Compound-specific isotope analysis (CSIA) is a valuable tool for assessing the fate of organic pollutants in the environment. However, the requirement of sufficient analyte mass for precise isotope ratio mass spectrometry combined with prevailing low environmental concentrations currently limits comprehensive applications to many micropollutants. Here, we evaluate the upscaling of solid-phase extraction (SPE) approaches for routine CSIA of herbicides. To cover a wide range of polarity, a SPE method with two sorbents (a hydrophobic hypercrosslinked sorbent and a hydrophilic sorbent) was developed. Extraction conditions, including the nature and volume of the elution solvent, the amount of sorbent and the solution pH, were optimized. Extractions of up to 10 L of agricultural drainage water (corresponding to up to 200000-fold pre-concentration) were successfully performed for precise and sensitive carbon and nitrogen CSIA of the target herbicides atrazine, acetochlor, metolachlor and chloridazon, and metabolites desethylatrazine, desphenylchloridazon and 2,6-dichlorobenzamide in the sub-g L-1-range. C-13/C-12 and N-15/N-14 ratios were measured by gas chromatography-isotope ratio mass spectrometry (GC/IRMS), except for desphenylchloridazon, for which liquid chromatography (LC/IRMS) and derivatization-GC/IRMS were used, respectively. The method validated in this study is an important step towards analyzing isotope ratios of pesticide mixtures in aquatic systems and holds great potential for multi-element CSIA applications to trace pesticide degradation in complex environments.
AU  - Torrentó, C.*
AU  - Bakkour, R.*
AU  - Glauser, G.*
AU  - Melsbach, A.
AU  - Ponsin, V.*
AU  - Hofstetter, T.B.*
AU  - Elsner, M.
AU  - Hunkeler, D.*
C1  - 55722
C2  - 46527
CY  - Thomas Graham House, Science Park, Milton Rd, Cambridge Cb4 0wf, Cambs, England
SP  - 2898–2908
TI  - Solid-phase extraction method for stable isotope analysis of pesticides from large volume environmental water samples.
JO  - Analyst
VL  - 144
IS  - 9
PB  - Royal Soc Chemistry
PY  - 2019
SN  - 0003-2654
ER  - 

TY  - JOUR
AB  - Apoptosis is a tightly regulated cellular process that plays an essential role in the development, aging, cancer biology, immune response, and pathogenesis of various diseases. Herein, we report a new SERS sensing strategy for in vitro sensitive detection of early apoptotic cells. The principle of this method is to in situ synthesize silver nanoparticles (AgNPs) on the phosphatidylserine (PS) of the apoptotic cell membrane during the early apoptosis, which enables distinguishing normal and apoptotic cells. The total assay time of the presented method is only 10 min, thus being faster, cheaper and simpler than current techniques for the detection of apoptosis. The intrinsic mechanism was verified by different approaches based on externalized phosphatidylserine. In addition, the detection process is real-time and label-free; i.e., the intrinsic SERS spectra from the cellular membrane are directly employed for apoptosis real-time detection, which avoids using additional chemical or biological reagents as external signal indicators. Therefore, our SERS approach may serve as a potentially practical tool for sensitive and real-time detection of early cell apoptosis, complementing the state-of-the-art strategies, e.g. flow cytometry. While further investigation is required to better understand the intrinsic mechanism of the in situ coating method, the current results may provide another choice for real-time detection of early apoptosis.
AU  - Zhou, H.*
AU  - Wang, Q.*
AU  - Yuan, D.*
AU  - Wang, J.*
AU  - Huang, Y.*
AU  - Wu, H.*
AU  - Jian, J.*
AU  - Yang, D.*
AU  - Huang, N.*
AU  - Haisch, C.*
AU  - Jiang, Z.*
AU  - Chen, S.
C1  - 48617
C2  - 41220
CY  - Cambridge
SP  - 4293-4298
TI  - Early apoptosis real-time detection by label-free SERS based on externalized phosphatidylserine.
JO  - Analyst
VL  - 141
IS  - 14
PB  - Royal Soc Chemistry
PY  - 2016
SN  - 0003-2654
ER  - 

TY  - JOUR
AB  - Studying cell-to-cell heterogeneity requires techniques which robustly deliver reproducible results with single-cell sensitivity. Through a new fabrication method for the microarrays for mass spectrometry (MAMS) platform, we now have attained robustness and reproducibility in our single-cell level mass spectrometry measurements that allowed us to combine single-cell MAMS-based measurements from different days and samples. By combining multiple measurements, we were able to identify three co-existing phenotypes in an isogenic population of Saccharomyces cerevisiae characterized by distinctively different levels of glycolytic intermediates.
AU  - Schmidt, A.M.*
AU  - Fagerer, S.R.*
AU  - Jefimovs, K.*
AU  - Buettner, F.
AU  - Marro, C.*
AU  - Siringil, E.C.*
AU  - Boehlen, K.L.*
AU  - Pabst, M.*
AU  - Ibáñez, A.J.*
C1  - 32495
C2  - 35074
CY  - Cambridge
SP  - 5709-5717
TI  - Molecular phenotypic profiling of a Saccharomyces cerevisiae strain at the single-cell level.
JO  - Analyst
VL  - 139
IS  - 22
PB  - Royal Soc Chemistry
PY  - 2014
SN  - 0003-2654
ER  - 

TY  - JOUR
AB  - An improved method for accurate and rapid assessment of the coenzyme Q10 (CoQ10) redox state using ultrahigh performance liquid chromatography tandem mass spectrometry was described, with particular attention given to the instability of the reduced form of CoQ10 during sample preparation, chromatographic separation and mass spectrometric detection. As highly lipophilic compounds in complex biological matrices, both reduced and oxidized forms of CoQ10 were extracted simultaneously from the tissue samples by methanol which is superior to ethanol and isopropanol. After centrifugation, the supernatants were immediately separated on a C18 column with isocratic elution using methanol containing 2 mM ammonium acetate as a non-aqueous mobile phase, and detected by positive electrospray ionization tandem mass spectrometry in multiple reaction monitoring (MRM) mode. Ammonium acetate as an additive in methanol provided enhanced mass spectrometric responses for both forms of CoQ10, primarily due to stable formation of adduct ions [M + NH4](+), which served as precursor ions in positive ionization MRM transitions. The assay showed a linear range of 8.6-8585 ng mL(-1) for CoQ10H2 and 8.6-4292 ng mL(-1) for CoQ10. The limits of detection (LODs) were 7.0 and 1.0 ng mL(-1) and limits of quantification (LOQs) were 15.0 and 5.0 ng mL(-1) for CoQ10H2 and CoQ10, respectively. This rapid extractive and analytical method could avoid artificial auto-oxidation of the reduced form of CoQ10, enabling the native redox state assessment. This reliable method was also successfully applied for the measurement of the CoQ10 redox state in liver tissues of mice exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin, revealing the down-regulated mitochondrial electron transport chain.
AU  - Tang, Z.*
AU  - Li, S.*
AU  - Guan, X.*
AU  - Schmitt-Kopplin, P.
AU  - Lin, S.*
AU  - Cai, Z.*
C1  - 31969
C2  - 34918
CY  - Cambridge
SP  - 5600-5604
TI  - Rapid assessment of the coenzyme Q10 redox state using ultrahigh performance liquid chromatography tandem mass spectrometry.
JO  - Analyst
VL  - 139
IS  - 21
PB  - Royal Soc Chemistry
PY  - 2014
SN  - 0003-2654
ER  - 

TY  - JOUR
AB  - A proof of concept for the simultaneous multi-parameter determination of three inflammation and sepsis parameters-TNFα, PCT and CRP-using a compact optical immunosensor is demonstrated. Harmonized assay conditions revealed standard curves with test midpoints (IC(50)) of 380 µg L(-1) for TNFα, 2300 µg L(-1) for PCT, and 2645 µg L(-1) for CRP.
AU  - Krämer, P.M.
AU  - Keß, M.
AU  - Kremmer, E.
AU  - Schulte-Hostede, S.
C1  - 4566
C2  - 28265
CY  - Cambridge
SP  - 692-695
TI  - Multi-parameter determination of TNFα, PCT and CRP for point-of-care testing.
JO  - Analyst
VL  - 136
IS  - 4
PB  - Royal Society of Chemistry
PY  - 2011
SN  - 0003-2654
ER  - 

TY  - JOUR
AB  - The speciation of trace element species in solid matrices like liver samples is still problematic due to two reasons. On the one hand direct methods with sufficient selectivity and sensitivity are currently not available. Therefore extraction procedures have to be applied which are often problematic in respect to species stability. On the other hand there are no reference materials with known amounts of metal proteins like metallothionein-isoforms (MT) and superoxide dismutase (SOD) for quality control. So the aim of this study was to develop and optimise procedures for the species-preserving extraction of the model compounds MT and SOD from liver samples. Spiking experiments were performed to overcome the lack of appropriate reference materials. In a first step the stability of the model species without liver matrix was investigated by the variation of several extraction parameters. The extractant and exposure to ultrasonic energy especially had a great influence on the recovery of the species while temperature, buffer concentration and atmospheric conditions were less critical. In a second step spiked liver samples were extracted with a selection of procedures taken from the literature. Most of these methods provided recoveries between 70% and 100%. Additionally the buffer concentration and the extractant-to-liver ratio were varied for optimisation. The metal balance of an extraction showed recoveries of 81% for Cd, 94% for Cu and 87% for Zn.
AU  - Nischwitz, V.
AU  - Michalke, B.
AU  - Kettrup, A.
C1  - 10369
C2  - 20664
SP  - 109-115
TI  - Optimisation of extraction procedures for metallothionein-isoforms and superoxide dismutase from liver samples using spiking experiments.
JO  - Analyst
VL  - 128
PY  - 2003
SN  - 0003-2654
ER  - 

TY  - JOUR
AB  - Because substantial evidence exists that sample drying and storage may have an effect on the extractability of trace metals from soils and sediments, we have examined whether such effects are also present for the typical fallout radionuclides 137Cs and 239+240Pu, for natural 210Pb, as well as for the corresponding stable elements Cs and Pb. For comparison, stable Mn was also included, because for this element a clear effect of drying and storage has been demonstrated recently. The sequential extraction procedure of Tessier was applied to two soils (a typical mineral soil with a low organic matter content, and the top layer of a forest soil with a high organic matter content). No substantial effect of air-drying and subsequent sample storage up to 30 weeks was detectable for 137Cs, 239+240Pu and 210Pb as well as for stable Cs and Pb. A clear effect of drying and subsequent sample storage was observable for stable Mn extracted from the mineral soil into fraction I, where its concentration increased continually with storage time. This supports an earlier observation reported in the literature for a similar soil. Nevertheless, because we did not observe such an effect for the soil with the high organic matter content, one should be careful about generalizing this result. The results also suggest that isotopic equilibrium between 137Cs and stable Cs as well as between 210Pb and stable Pb in the two soils is approximately established.
AU  - Bunzl, K.
AU  - Schimmack, W.
AU  - Schramel, P.
AU  - Suomela, M.*
C1  - 21123
C2  - 19161
SP  - 1383-1387
TI  - Effect of sample drying and storage time on the extraction of fallout 239+240Pu, 137Cs and natural 210Pb as well as of satble Cs, Pb and Mn from soils.
JO  - Analyst
VL  - 124
PY  - 1999
SN  - 0003-2654
ER  - 

TY  - JOUR
AB  - The vertical activity distributions of fallout 238Pu, 239+240Pu 241 Am, 137Cs and 137Cs in a forest soil (Hapludult) were determined at several locations in a spruce stand separately according to their origin (global fallout or Chernobyl fallout). To determine the rate of migration of these radionuclides in each soil horizon, the observed depth profiles of the radionuclides were evaluated with a compartment model. In the top organic horizons (LOf1 and Of2), the migration rates for all radionuclides from both sources were above 0.5 cm per year. In the Oh horizon the migration rates observed for global fallout Pu, Am and Cs were similar (0.2-0.4 cm per year). Compared with Pu, however, the mobility of Am is slightly, but statistically significantly, enhanced. The highest rate in this layer was found for Chernobyl-derived radiocaesium (2 cm per year). In the layers of the mineral horizon (depth 0-2, 2-5 and 5-10 cm) the observed migration rates were very similar for global fallout Pu (0.08-0.7 cm per year) and Am (0.1-2 cm per year). In comparison, the migration rate of global fallout radiocaesium was about half in each layer. The highest rate was observed again for Chernobyl-derived radiocaesium (0.5-3 cm per year).
AU  - Bunzl, K.W.
AU  - Kracke, W.
AU  - Schimmack, W.
C1  - 40582
C2  - 38766
SP  - 469-474
TI  - Vertical migration of Plutonium-239 + -240, Americium-241 and Caesium-137 fallout in a forest soil under spruce.
JO  - Analyst
VL  - 117 3
PY  - 1992
SN  - 0003-2654
ER  -