title: Validation and performance comparison of two carbon isotope ratio methods to control the misuse of androgens in humans.
abstract: Carbon isotope ratio of androgens in urine specimens is routinely determined to exclude an abuse of testosterone or testosterone prohormones by athletes. Increasing application of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) in the last years for target and systematic investigations on samples has resulted in the demand for rapid sample throughput as well as high selectivity in the extraction process particularly in the case of conspicuous samples. For that purpose, we present herein the complimentary use of an SPE-based assay and an HPLC fractionation method as a two-stage strategy for the isolation of testosterone metabolites and endogenous reference compounds prior to GC/C/IRMS analyses. Assays validation demonstrated acceptable performance in terms of intermediate precision (range: 0.1-0.4 per thousand) and Bland-Altman analyses revealed no significant bias (0.2 per thousand). For further validation of this two-stage analyses strategy, all the specimens (n=124) collected during a major sport event were processed.
authors.affiliation: Swiss Laboratory for Doping Analyses, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Ch. des Croisettes 22, 1066 Epalinges, Switzerland. Christophe.Saudan@chuv.ch
authors.forename: Christophe
authors.initials: C
authors.lastname: Saudan
authors.forename: Caroline
authors.initials: C
authors.lastname: Emery
authors.forename: François
authors.initials: F
authors.lastname: Marclay
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Strahm
authors.forename: Patrice
authors.initials: P
authors.lastname: Mangin
authors.forename: Martial
authors.initials: M
authors.lastname: Saugy
mesh_terms: D000728:Androgens / Q000652:urine*; D002247:Carbon Isotopes / Q000032:analysis*; D002849:Chromatography, Gas / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004300:Doping in Sports; D013058:Mass Spectrometry / Q000379:methods; D015813:Substance Abuse Detection / Q000379:methods*; D013739:Testosterone / Q000652:urine*
chemical_list: D000728:Androgens; D002247:Carbon Isotopes; D013739:Testosterone