Simultaneous Detection of Androgen and Estrogen Abuse
in Breeding Animals by Gas Chromatography–Mass Spectrometry/Combustion/Isotope
Ratio Mass Spectrometry (GC-MS/C/IRMS) Evaluated against Alternative
Methods
The administration of synthetic homologues
of naturally occurring
steroids can be demonstrated by measuring <sup>13</sup>C/<sup>12</sup>C isotopic ratios of their urinary metabolites. Gas chromatography–mass
spectrometry/combustion/isotope ratio mass spectrometry (GC-MS/C/IRMS)
was used in this study to appraise in a global approach isotopic deviations
of two 17β-testosterone metabolites (17α-testosterone
and etiocholanolone) and one 17β-estradiol metabolite (17α-estradiol)
together with those of 5-androstene-3β,17α-diol as endogenous
reference compound (ERC). Intermediate precisions of 0.35‰,
1.05‰, 0.35‰, and 0.21‰, respectively, were observed
(<i>n</i> = 8). To assess the performance of the analytical
method, a bull and a heifer were treated with 17β-testosterone
propionate and 17β-estradiol-3-benzoate. The sensitivity of
the method permitted the demonstration of 17β-estradiol treatment
up to 24 days. For 17β-testosterone treatment, the detection
windows were 3 days and 24 days for the bull and the heifer, respectively.
The capability of GC-MS/C/IRMS to demonstrate natural steroid abuse
for urinary steroids was eventually compared to those of mass spectrometry
(LC-MS/MS) when measuring intact steroid esters in blood and hair