13C/12C isotope ratio MS analysis of testosterone, in chemicals and pharmaceutical preparations

The C-13/C-12 ratio can be used to detect testosterone misuse in sport because (semi)-synthetic testosterone is supposed to have a C-13 abundance different from that of endogenous natural human testosterone. In this study, gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) analysis for the measurement of the delta C-13% value of testosterone from esterified forms of 13 pharmaceutical preparations, six reagent grade chemicals and three bulk materials (raw materials used in pharmaceutical proarations) obtained world-wide was investigated after applying a strong acidic solvolytic procedure. Mean delta C-13% values of non esterified (free) testosterone from chemicals and bulk materials of several testosterone esters were in the range: -25.91/-32.82% while the value obtained for a (semi)-synthetic, reagent gr adc, free testosterone was -27/.36%. The delta C-13% results obtained For testosterone from the pharmaceuticals investigated containing testosterone esters were quite homogeneous (mean and S.D. of delta C-13% values of free testosterone 27.43 +/- 0.76%), being the range between -26.18 and -30.04%. Values described above were clearly different From those reported by several authors for endogenous natural human testosterone and its main metabolites excreted into the urine in non-consumers of testosterone (delta C-13% range: from -21.3 to -24.4%), while they were similar to those of urinary testosterone and metabolites from individuals treated with testosterone esters and testosterone precursors. This finding justifies the fact that administration of these pharmaceutical formulation led to a statistical decrease of carbon isotope ratio of urinary testosterone and its main metabolites in treated subjects. (C) 2001 Elsevier Science B.V. All rights reserved.