TY - JOUR AB - Dried blood spot (DBS) samples are already successfully used in newborn screening and pharmacological analyses. The application of DBS matrix to further metabolomic methods will considerably extend the analytical options for the diagnostics of metabolic diseases. We present an MS/MS based method for the simultaneous extraction and quantification of 188 metabolites from dried blood spots. We provide a sensitive and reproducible method that adapts the Absolute IDQ™ p180 kit of Biocrates to the DBS matrix for the quantification of metabolites of different substance classes including amino acids, biogenic amines, free carnitine, acylcarnitines, hexoses, glycerophospholipids, lysophosphatidylcholines, phosphatidylcholines, and sphingolipids. AU - Zukunft, S. AU - Sorgenfrei, M. AU - Prehn, C. AU - Möller, G. AU - Adamski, J. C1 - 26254 C2 - 32146 SP - 1295-1305 TI - Targeted metabolomics of dried blood spot extracts. JO - Chromatographia VL - 76 IS - 19-20 PB - Springer PY - 2013 SN - 0009-5893 ER - TY - JOUR AB - Reversed (RP-HPLC) and normal phase chromatographic (NP-HPLC) separations have been developed for diastereomers ofN-acyl-1-methyl-1,2,3,4-tetrahydo-β-carbolines which are acylated derivatives of simple natural β-carboline alkaloids. Separations of derivatives having different acyl moieties in theO,O-diacyl-tartaric acid ester subtituent differed remarkably. Little or no resolution in either NP-HPLC or RP-HPLC could be achieved with the diacetyl-tartrate derivative. Base-line separation by RP-HPLC but no separation by NP-HPLC was possible with the bulkier and more apolar dipivaloyl derivative. Retention order of the bis-benzoylated diastereomers was reversed and separation time increased dramatically by RP-HPLC. Good separation of the medium polarity, but rigid,N-camphanyl derivative by NP-HPLC has been achieved, whereas RP-HPLC could not be used for separation of these diastereomers. Separability of different diastereomers was highly dependent on polarity and rigidity of the derivatizingN-acyl moieties. Conformational analysis by molecular mechanics and comparison of the lowest energy conformational states of the diastereomers was applied to rationalise separation-retention behaviour of stereoisomers by RP-HPLC. AU - Fekete, J.* AU - Milen, M.* AU - Hazai, L.* AU - Poppe, L.* AU - Szantay, Cs.* AU - Kettrup, A. AU - Gebefügi, I. C1 - 10270 C2 - 20893 SP - 147-153 TI - Comparative Study on Separation of Diastereomers by HPLC. JO - Chromatographia VL - 57 IS - 3 PY - 2003 SN - 0009-5893 ER - TY - JOUR AB - A method for dead time determination in reversed-phase capillary electrochromatography (RP-CEC) with methacrylate-based monolithic stationary phases has been presented based on homologue series method. The dead times measured with homologue series method and thiourea, a commonly used electroosmotic flow (EOF) marker are compared under various conditions, such as the type and the concentration of organic modifier, ionic strength, and applied voltage. Results show that the former one is larger than the latter one. Under high ionic strength and low applied voltage, EOF velocity measured by thiourea is close to that determined by homologue series method. AU - Ping, G.* AU - Zhang, W.* AU - Zhang, L.* AU - Zhang, Li.* AU - Shan, Y.`* AU - Zhang, Y.* AU - Schmitt-Kopplin, P. AU - Kettrup, A. C1 - 4331 C2 - 21783 SP - 803-806 TI - Method for dead time determination in reversed-phase capillary electrochromatography with methacrylate-based stationary phases. JO - Chromatographia VL - 58 IS - 11 PY - 2003 SN - 0009-5893 ER - TY - JOUR AB - Separation of nucleosides by capillary electrochromatography with a methacrylate-based monolithic column is described. Because the nucleosides are relatively hydrophilic compounds, chromatographic parition is very weak on non-polar stationary phases. A small quantity of organic modifier is usually required to increase their retention factars but, because the wettability of the stationary phase by the mobile phase is rather poor, bubble formation can be a significant problem. This situation was improved by use of a polymeric monolithic column with higher level charged monomer in the polymerization mixlure, because of the presence of charged moieties on the surface of the monolithic stationary phase. The very high stability under conditions of very low organic modifier concentration used in the experiment showed that the wettability of the stationary phase by the mobile phase was satisfactory. The effect of pH, orgonic modifier content, and applied voltage on the separation was investigated. Baseline separction of six nucleosides was achieved within 4.5 min on this type of column. Because of the presence of charged moieties and butyl groups on the surface of the monolithic column, the mechanism of separation might involve both ion-exchange and hydrophobic interactions. AU - Ping, G.* AU - Zhang, W.* AU - Zhang, L.* AU - Schmitt-Kopplin, P. AU - Zhang, Y.* AU - Kettrup, A. C1 - 10271 C2 - 21000 SP - 629-633 TI - Rapid Separation of Nucleosides by Capillary Electrochromatography with a Methacrylate-Based Monolithic Stationary Phase. JO - Chromatographia VL - 57 IS - 9 PY - 2003 SN - 0009-5893 ER - TY - JOUR AB - Polymethacrylate-based monolithic columns were prepared for capillary electrochromatography (CEC) byin situ copolymerization of butyl methacrylate (BMA), 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), and ethylene dimethacrylate (EDMA) in the presence of a porogen in fused-silica capillaries of 100 μm I.D. The abnormal phenomenon that retention factors for neutral species decreases with applied voltage in CEC was observed. Capillary electrophoresis (CE) instruments usually require a period of time to increase voltage from 0 kV to desired value, which is called as ramp time. Such ramp time and any error in the determination of dead time should be taken into account during the accurate calculation of retention factors. After the correction of the retention factors, the plots of the corrected factors for alkylbenzene versus applied voltage were made, the absolute value of the plot slopes are less than 1.8×10−4, which indicates that the corrected retention times for neutral species do not show any dependence on applied voltage. Further, the plats of the corrected retention times for acidic and basic compounds versus the reciprocal of applied voltage were drawn, where the target compounds were eluted in neutral form. The very nice linearity of the plots was obtained. The linear correlation coefficients are over 0.999. Here, the slopes of the plots representLeff⋅Ltot⋅(l+k)μeo, which indicates that retention factors for the test compounds are constants under a given separation condition. AU - Ping, G.* AU - Zhang, W.* AU - Zhang, L.* AU - Schmitt-Kopplin, P. AU - Kettrup, A. AU - Zhang, Y.* C1 - 10272 C2 - 21144 SP - 777-781 TI - Abnormal Phenomenon of the Dependence of the Retention Factors for Uncharged Species on Applied Voltage in Capillary Electrochromatography. JO - Chromatographia VL - 57 IS - 11 PY - 2003 SN - 0009-5893 ER - TY - JOUR AB - Reversed phase HPLC methods for the determination of two metabolites of albendazole in cow's milk are described. Albendazole is an anthelmintic agent used both in veterinary and human practice. Its main metabolites are albendazole-sulfoxide and albendazole-sulfone. The separation of the two metabolites was performed on a μ-Bondapak C-18 column using an acetonitrile/methanol/phosphate buffer as mobile phase, with detection at 290 nm. For the sample preparation of the milk samples we used solid phase extraction. A new sample treatment optimisation procedure is also presented for the sample preparation method. Since sample preparation is a critical step in the analysis of residues in biological samples, the second part of our publication describes an optimisation using Taguchi's methodology that increased recovery, accuracy and reliability. After optimisation of the sample preparation, the limit of detection was 10 ng mL−1 milk and the recovery was 70–80% in the concentration range of 30–1000 ng mL−1 milk for both metabolities. AU - Romvari, Z.* AU - Fekete, J.* AU - Kemeny, S.* AU - Pokol, G.* AU - Gebefügi, I. AU - Kettrup, A. C1 - 21136 C2 - 19176 SP - 777-784 TI - Determination of two metabolites of albendazole, albendazole-sulfoxide and albendazole-sulfone in cow's milk using an HPLC method: A systematic approach to optimise extraction conditions. JO - Chromatographia VL - 48 IS - 11 PY - 1998 SN - 0009-5893 ER - TY - JOUR AB - Short chain aliphatic acids are important components of the dissolved organic matter in silage effluents. Although ion exclusion chromatography offers some advantages for the analysis of these compounds, no attempt has yet been made to prove the suitability of this method for silage effluent analysis. In order to gain experience in this field, the separation characteristics of a Dionex ion exclusion column (IonPac-ICE As5) have been evaluated, the separation conditions have been improved, and several sample clean-up methods have been checked. Ten effluents generated during silaging of five different crops were collected from Bavarian farms and analyzed. Lactic and acetic acids were the predominant aliphatic acids. Pyruvic, formic, propionic, and succinic acid were detected in all samples, whereas glyceric and iso-citric acid were found in a few samples only. If some restrictions of substance specificity and separation efficiency can be accepted, the analytical method presented will be a reliable tool for the analysis of carboxylic acids in silage effluents. AU - Fischer, K.* AU - Corsten, C. AU - Leidmann, P. AU - Bieniek, D. AU - Kettrup, A.* C1 - 33941 C2 - 38934 SP - 43-51 TI - Determination of short chain aliphatic acids in silage effluents by ion exclusion chromatography. JO - Chromatographia VL - 38 IS - 1-2 PY - 1994 SN - 0009-5893 ER - TY - JOUR AB - A high-performance liquid chromatographic method has been developed for detecting and quantifying dimethyl sulphoxide (DMSO) in water and especially in wastewater. The detection limit for the quantification of DMSO is 0.5 ppm. AU - Thumm, W. AU - Freitag, D. AU - Kettrup, A. C1 - 40848 C2 - 38531 SP - 461-462 TI - Determination and quantification of dimethyl sulphoxide by HPLC. JO - Chromatographia VL - 32 IS - 9-10 PY - 1991 SN - 0009-5893 ER - TY - JOUR AB - The advantages of liquid chromatography with diode array and mass spectrometric detection are described for the direct characterization of the photodegradation products of Fenitrothion, Atrazine and Diuron in distilled water and artifical seawater samples. The photodegradation (UV λ>290 nm) of the herbicides Atrazine and Diuron was examined in distilled water and in artificial seawater containing humic acids. Major photodegradation products were hydroxyatrazine and Monuron, respectively. The results showed a faster degradation in seawater as compared to distilled water for Atrazine whereas for Diuron a quenching effect was observed thus retarding photodegradation. The photodegradation of Fenitrothion was also investigated. For this pesticide, hydrolysis predominates in seawater and photolysis is very slow in distilled water, so that acetone was needed as photosensitizer. AU - Durand, G. AU - Barcelo, D. AU - Albaigés, J. AU - Mansour, M. C1 - 18180 C2 - 11390 SP - 120-124 TI - Utilisation of Liquid Chromatography in Aquatic Photodegradation Studies of Pestizides: A Comparison Between Distilled Water and Seawater. JO - Chromatographia VL - 29 IS - 3 PY - 1990 SN - 0009-5893 ER - TY - JOUR AB - The advantages of liquid chromatography with diode array and mass spectrometric detection are described for the direct characterization of the photodegradation products of Fenitrothion, Atrazine and Diuron in distilled water and artifical seawater samples. The photodegradation (UV λ>290 nm) of the herbicides Atrazine and Diuron was examined in distilled water and in artificial seawater containing humic acids. Major photodegradation products were hydroxyatrazine and Monuron, respectively. The results showed a faster degradation in seawater as compared to distilled water for Atrazine whereas for Diuron a quenching effect was observed thus retarding photodegradation. The photodegradation of Fenitrothion was also investigated. For this pesticide, hydrolysis predominates in seawater and photolysis is very slow in distilled water, so that acetone was needed as photosensitizer. AU - Durand, G.* AU - Barcelo, D.* AU - Albaigés, J.* AU - Mansour, M. C1 - 41636 C2 - 36473 SP - 120-124 TI - Utilisation of liquid chromatography in aquatic photodegradation studies of pesticides: A comparison between distilled water and seawater. JO - Chromatographia VL - 29 IS - 3-4 PY - 1990 SN - 0009-5893 ER -