Stable isotope ratio profiling of testosterone preparations

Gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) is the preferred method of confirming the administration of exogenous testosterone by athletes. This relies on synthetic testosterone preparations being depleted in C-13 compared to natural testosterone. There is concern, however, about the existence of synthetic testosterone products that are unexpectedly C-13-enriched and which may allow athletes to circumvent the current GC-C-IRMS test. Further to the reported studies of legitimate pharmaceutical-grade testosterone products, a detailed analysis of seized materials from border-level seizures was required to obtain intelligence concerning trends in 'black market' testosterone manufacture and distribution. The sample set collected for this study between 2006 and 2009 inclusive provided a delta C-13 range (n=266) of -22.9 parts per thousand to -32.6 parts per thousand with mean and median values of -28.4 parts per thousand and -28.6 parts per thousand, respectively. Within this distribution there were 24 samples (9%) confirmed to have delta C-13 values in the range reported for endogenous urinary steroid metabolites (>= -25.8 parts per thousand). The benefit of delta C-13 profiling for testosterone preparations was demonstrated by the ability to identify specific seized products that can be target tested for future intelligence purposes. In addition, the potential of stable hydrogen isotope ratio (H-2/H-1; delta H-2) discrimination to complement delta C-13 analysis was investigated. Methodologies for the determination of delta H-2 values by gas chromatography-thermal conversion-isotope ratio mass spectrometry (GC-TC-IRMS) were developed to provide a delta H-2 range (n=173) of -177 parts per thousand to -268 parts per thousand with mean and median values of -231 parts per thousand and -234 parts per thousand, respectively. Copyright (C) 2010 John Wiley & Sons, Ltd.