Steroidal isomers with uniform mass spectra of their per-TMS derivatives:: Synthesis of 17-hydroxyandrostan-3-ones, androst-1-, and -4-ene-3,17-diols

In human sports doping control analysis most of the steroids are analyzed after enzymatic hydrolysis of the glucuronides as per-trimethylsilyl (TMS) derivatives applying gas chromatography-mass spectrometry (GC-MS). According to the recommendations of the World Anti-Doping Agency the identification of analytes should be based on retention time and on mass spectrometric characterization. This study shows that the bis-TMS derivatives of 16 specific C19 steroids, namely the stereoisomers of S xi-androst-l-ene-3 xi,17 xi-diol (8 isomers), androst-4-ene-3 xi,17 xi-diol (4 isomers), and 17 xi-hydroxy-5 xi-androstan-3-one (4 isomers), reveal very similar mass spectra. As a rule, when taking the retention times, which are provided as Kovac indices for all these isomers, into account, a restriction to two or three possible isomers is possible. Reliable identification should additionally include a comparison of the retention times of the analytes with the reference compounds measured concomitantly. In some cases standard addition may be appropriate. Due to the limited availability; the above mentioned isomers were synthesized by reduction of the corresponding alpha,beta-unsaturated oxo, steroids either with K-Selectride or by catalytic hydrogenation (Pd/C as catalyst). The products of the reactions were identified by means of nuclear magnetic resonance (NMR) characterization and by further reduction to the corresponding 5 xi-androstane-3 xi,17 xi-diols and GC-MS comparison with commercially available reference standards. (c) 2007 Elsevier Inc. All rights reserved.