title: Gas chromatography-combustion-isotope ratio mass spectrometry analysis of 19-norsteroids: application to the detection of a nandrolone metabolite in urine.
abstract: Determination of whether the major metabolite of nandrolone in urine, 19-norandrosterone (19-NA), is exogenous or endogenous in origin is one of the most exciting challenges for antidoping laboratories. Gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) can be used to differentiate these two origins by carbon isotopic ratio analysis. A complete method for purification of 19-NA in urine has been established. Acetylated ketosteroids, and in particular 19-NA, are isolated from the urine matrix before analysis after hydrolysis and purification of urine by reversed-phase and normal solid-phase extraction. The limit of detection for 19-NA was about 60 ng with recoveries of 54-60%. Evidence of exogenous administration of 19-NA may be established from isotope ratio determination from the 13C/12C ratios of several synthetic 19-norsteroids compared to those obtained for endogenous steroids.
authors.affiliation: Laboratoire National de Dépistage du Dopage, CREPS, Chatenay Malabry, France. jc.mathurin@wanadoo.fr
authors.forename: J C
authors.initials: JC
authors.lastname: Mathurin
authors.forename: V
authors.initials: V
authors.lastname: Herrou
authors.forename: E
authors.initials: E
authors.lastname: Bourgogne
authors.forename: L
authors.initials: L
authors.lastname: Pascaud
authors.forename: J
authors.initials: J
authors.lastname: de Ceaurriz
mesh_terms: D004300:Doping in Sports; D004962:Estranes / Q000652:urine*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D004962:Estranes; C036015:19-norandrosterone