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51.
Van Eenoo P Van Gansbeke W De Brabanter N Deventer K Delbeke FT 《Journal of chromatography. A》2011,1218(21):3306-3316
The use of performance enhancing drugs in sports is prohibited. For the detection of misuse of such substances gas chromatography or liquid chromatography coupled to mass spectrometry are the most frequently used detection techniques. In this work the development and validation of a fast gas chromatography tandem mass spectrometric method for the detection of a wide range of doping agents is described. The method can determine 13 endogenous steroids (the steroid profile), 19-norandrosterone, salbutamol and 11-nor-Δ9-tetrahydrocannabinol.9carboxylic acid in the applicable ranges and to detect qualitatively over 140 substances in accordance with the minimum required performance levels of the World Anti-Doping Agency in 1ml of urine. The classes of substances included in the method are anabolic steroids, β2-agonists, stimulants, narcotics, hormone antagonists and modulators and beta-blockers. Moreover, using a short capillary column and hydrogen as a carrier gas the run time of the method is less than 8min. 相似文献
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Henk Schierbeek Denise Rook Frans W. J. te Braake Kristien Y. Dorst Gardi Voortman Jean‐Philippe Godin Laurent‐Bernard Fay Johannes B. van Goudoever 《Rapid communications in mass spectrometry : RCM》2009,23(18):2897-2902
Determination of glutathione kinetics using stable isotopes requires accurate measurement of the tracers and tracees. Previously, the precursor and synthesized product were measured with two separate techniques, liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) and gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). In order to reduce sample volume and minimize analytical effort we developed a method to simultaneously determine 13C‐glutathione as its dimeric form (GSSG) and its precursor [1‐13C]glycine in a small volume of erythrocytes in one single analysis. After having transformed 13C‐glutathione into its dimeric form GSSG, we determined both the intra‐erythrocytic concentrations and the 13C‐isotopic enrichment of GSSG and glycine in 150 µL of whole blood using liquid chromatography coupled to LC/IRMS. The results show that the concentration (range of µmol/mL) was reliably measured using cycloleucine as internal standard, i.e. with a precision better than 0.1 µmol/mL. The 13C‐isotopic enrichment of GSSG and glycine measured in the same run gave reliable values with excellent precision (standard deviation (sd) <0.3‰) and accuracy (measured between 0 and 5 APE). This novel method opens up a variety of kinetic studies with relatively low dose administration of tracers, reducing the total cost of the study design. In addition, only a minimal sample volume is required, enabling studies even in very small subjects, such as preterm infants. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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It is shown that one of the two conjugate solutions compatible with the AB part of an ABX system can easily be eliminated, at an early stage of the analysis, by considering intensity ratios in the X region. 相似文献
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We construct two types of twists for the SU(N→∞) twisted-Eguchi-Kawai model, which mimic a periodic boundary condition in the temporal direction only and over an arbitrary extent N0. In this way we introduce finite temperature (T=N0?1 in lattice units) in the single-point model. In weak coupling one gets the correct planar expansion. 相似文献
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The present kinetic data on the accelerating action of sulfur in the base catalyzed racemisation of cyclic dipeptides () support the explanation of Barber and Jones () for the α center and suggest further a 1,3- and 1,4-interaction of -S- with the amide N-atom () for the α′ center. 相似文献
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M. Anteunis F. Borremans R. Van Den Bossche G. Verhegge 《Magnetic resonance in chemistry : MRC》1972,4(4):481-487
PMR parameters of some methylene substituted oxiranes are obtained from INDOR experiments on the ABXMN spin systems. Compounds investigated include safrol- and bromosafrol epoxide and β-phenoxypropylene oxide. For the latter compound all the relative signs (except for some long range couplings) were obtained and certain of these are in contradiction with those reported 2 in β-chloropropylene oxide. ‘Non-classical’ long range coupling is also noted and differs in pathway from that reported previously.2. 相似文献