Journal ArticleDOI
Determination of 13C/12C ratios of endogenous urinary steroids: method validation, reference population and application to doping control purposes.
Thomas Piper,Ute Mareck,Hans Geyer,Ulrich Flenker,Mario Thevis,Petra Platen,Wilhelm Schänzer +6 more
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TLDR
The application of a comprehensive gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS)-based method for stable carbon isotopes of endogenous urinary steroids is presented, which covers repeatability and reproducibility.Abstract:
The application of a comprehensive gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS)-based method for stable carbon isotopes of endogenous urinary steroids is presented. The key element in sample preparation is the consecutive cleanup with high-performance liquid chromatography (HPLC) of underivatized and acetylated steroids, which allows the isolation of ten analytes (11beta-hydroxyandrosterone, 5alpha-androst-16-en-3beta-ol, pregnanediol, androsterone, etiocholanolone, testosterone, epitestosterone, 5alpha-androstane-3alpha,17beta-diol, 5beta-androstane-3alpha,17beta-diol and dehydroepiandrosterone) from a single urine specimen. These steroids are of particular importance to doping controls as they enable the sensitive and retrospective detection of steroid abuse by athletes. Depending on the biological background, the determination limit for all steroids ranges from 5 to 10 ng/mL for a 10 mL specimen. The method is validated by means of linear mixing models for each steroid, which covers repeatability and reproducibility. Specificity was further demonstrated by gas chromatography/mass spectrometry (GC/MS) for each analyte, and no influence of the sample preparation or the quantity of analyte on carbon isotope ratios was observed. In order to determine naturally occurring (13)C/(12)C ratios of all implemented steroids, a reference population of n = 61 subjects was measured to enable the calculation of reference limits for all relevant steroidal Delta values.read more
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Chiral Toxicology: It's the Same Thing…Only Different
TL;DR: Chiral substances possess a unique architecture such that, despite sharing identical molecular formulas, atom-to-atom linkages, and bonding distances, they cannot be superimposed as discussed by the authors.
REVIEW Chiral Toxicology: It's the Same Thing ... Only Different
TL;DR: Environmental toxicology provides several examples in which compound bioaccumulation, persistence, and toxicity show chiral dependence, and chiral analysis has been applied to illicit drug preparations and biological specimens, with the potential to assist in determination of cause of death and aid in the correct interpretation of substance abuse and "doping" screens.
Journal ArticleDOI
Detection of the misuse of steroids in doping control.
TL;DR: The list of prohibited substances of the World Anti-Doping Agency (WADA) classifies the administration of several steroids in sports as doping, and their analysis is generally performed using urine specimen as matrix.
Journal ArticleDOI
Confounding factors and genetic polymorphism in the evaluation of individual steroid profiling
TL;DR: An extensive literature review of the multiple factors that could influence the quantitative levels and ratios of endogenous steroids in urine matrix is performed to show the complex process of quantifying the steroid profile within WADA-accredited laboratories.
Journal ArticleDOI
Recent developments in the use of isotope ratio mass spectrometry in sports drug testing
TL;DR: For more than 15 years, doping control laboratories focused on the carbon isotope ratios of endogenous steroids to distinguish between naturally elevated steroid profile parameters and illicit administration of steroids, but the number of different steroids under investigation by isotope ratio mass spectrometry has recently grown considerably.
References
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Isotopic standards for carbon and oxygen and correction factors for mass-spectrometric analysis of carbon dioxide
TL;DR: In this paper, Niee's and Solenhofen standards were compared to the Chicago PDB standard for carbon and oxygen isotope ratios, and the correction factors for instrumental effects and for the nature of the mass spectra were derived.
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Overview of Steroidogenic Enzymes in the Pathway from Cholesterol to Active Steroid Hormones
Anita H. Payne,Dale B. Hales +1 more
TL;DR: This review presents a detailed description of the enzymes involved in the biosynthesis of active steroid hormones, with emphasis on the human and mouse enzymes and their expression in gonads, adrenal glands, and placenta.
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The concentration and isotopic abundances of atmospheric carbon dioxide in rural areas
TL;DR: In this article, the isotopic abundances of C13 and O18 were analyzed for carbon dioxide reporting, in addition to concentration in air, in order to explain the correlation observed for all samples between C13 isotope abundance and concentration of carbon dioxide in air.
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The application and interpretation of Keeling plots in terrestrial carbon cycle research
Diane E. Pataki,James R. Ehleringer,Lawrence B. Flanagan,Dan Yakir,David R. Bowling,Christopher J. Still,Christopher J. Still,Nina Buchmann,Jed O. Kaplan,Joseph A. Berry +9 more
TL;DR: In this paper, the authors used the Keeling plot method to determine the carbon isotope composition of ecosystem respiration (d 13 CR) in order to better understand the processes controlling ecosystem isotope discrimination.
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Applied gas chromatography coupled to isotope ratio mass spectrometry
TL;DR: Due to its ability to measure isotope distribution at natural abundance level with great accuracy and high precision, GC-C-IRMS has increasingly become the method of choice in authenticity control of foodstuffs and determination of origin in archaeology, geochemistry, and environmental chemistry.