Use of silylating agents for the identification of hydroxylated steroids by gas chromatography and gas chromatography-mass spectrometry. Discrimination between phenolic and alcoholic hydroxyl groups.

A phenolic trimethylsilyl (TMS) group was selectively exchanged for a dimethylalkylsilyl (DMAS) group on a gas chromatographic column by use of sandwich injection technique with DMAS-imidazole, and a TMS ether derivative of a phenolic steroid was converted into a DMAS ether or a mixed TMS and DMAS ether derivative with over 95% recovery. The selective exchange reaction seemed to be caused by the difference in lability between the ethereal TMS linkages to phenolic and alcoholic hydroxyl groups. This selectivity was found to be useful for discriminating gas chromatographically between the phenolic and alcoholic hydroxyl groups in steroids.