Determination of plasma testosterone by combined gas chromatography-mass spectrometry

Abstract

A rapid quantitative method has been developed for the estimation of testosterone in human male peripheral plasma using the technique of combined gas chromatography-mass spectrometry. Plasma samples are submitted to a simple extraction procedure and after forming the bromomethyldimethylsilyl ether derivative are analysed without further purification on a 50 cm 2.0% OV-1 column. Deuterium-labelled testosterone is added to the plasma as an internal standard and quantitation effected by multiple peak monitoring at low resolving power. The standard deviation of the method is 7.2% of the mean value for a determination at the level of 0.81 μg/100 ml plasma. In addition, it is shown that the method has sufficient inherent sensitivity to be applicable to the estimation of testosterone in female plasma. In an alternative technique, after a preliminary thin-layer separation, the same samples are introduced directly into the mass spectrometer source and analysed at a higher resolving power. An analysis of the limitations imposed by the purity of the stable isotope-labeled compound used as internal standard in multiple peak monitoring methods is also presented.