title: A comprehensive procedure based on gas chromatography-isotope ratio mass spectrometry following high performance liquid chromatography purification for the analysis of underivatized testosterone and its analogues in human urine.
abstract: The confirmation by GC/C/IRMS of the exogenous origin of pseudo-endogenous steroids from human urine samples requires extracts of adequate purity. A strategy based on HPLC sample purification prior to the GC/C/IRMS analysis of human urinary endogenous androgens (i.e. testosterone, androsterone and/or androstenediols), is presented. A method without any additional derivatization step is proposed, allowing to simplify the urine pretreatment procedure, leading to extracts free of interferences permitting precise and accurate IRMS analysis, without the need of correcting the measured delta values for the contribution of the derivatizing agent. The HPLC extracts were adequately combined to both reduce the number of GC/C/IRMS runs and to have appropriate endogenous reference compounds (ERC; i.e. pregnanediol, 11-keto-etiocholanolone) on each GC-IRMS run. The purity of the extracts was assessed by their parallel analysis by gas chromatography coupled to mass spectrometry, with GC conditions identical to those of the GC/C/IRMS assay. The method has been validated according to ISO17025 requirements (within assay precision below 0.3‰(13)C delta units and between assay precision below 0.6‰(13)C delta units for most of the compounds investigated) fulfilling the World Anti-Doping Agency requirements.
authors.affiliation: Laboratorio Antidoping, Federazione Medico Sportiva Italiana, Rome, Italy. xavier.delatorre@gmail.com
authors.forename: Xavier
authors.initials: X
authors.lastname: de la Torre
authors.forename: Cristiana
authors.initials: C
authors.lastname: Colamonici
authors.forename: Davide
authors.initials: D
authors.lastname: Curcio
authors.forename: Francesco
authors.initials: F
authors.lastname: Molaioni
authors.forename: Francesco
authors.initials: F
authors.lastname: Botrè
mesh_terms: D002623:Chemistry Techniques, Analytical / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D013739:Testosterone / Q000737:chemistry / Q000378:metabolism / Q000652:urine*
chemical_list: D013739:Testosterone