Detection of 17alpha-hydroxyprogesterone caproate in equine plasma by gas chromatography/tandem mass spectrometry.

A method was developed for the analysis of the synthetic progestin 17alpha-hydroxyprogesterone caproate in equine plasma following its administration by intramuscular injection. The method employed a reversed-phase solid-phase extraction followed by enol-trimethylsilylation and analysis by gas chromatography/tandem mass spectrometry. The intact ester was detectable in the plasma for up to 2 weeks after a single therapeutic dose, and was found to be stable in equine whole blood for at least 2 months. Copyright (c) 2006 John Wiley & Sons, Ltd.