Analytical Sciences

An Improved Method for the Capillary Gas Chromatographic Derivatization of Polyhydroxylated Steroids Having tert-Hydroxyl Groups

Takashi IIDA,*  Keisuke SHIRAISHI,* Shoujiro OGAWA,* Junichi GOTO,** and Toshio NAMBARA**

*Department of Chemistry, College of Humanities & Sciences, Nihon University, Setagaya, Sakurajousui, Tokyo 156-8550, Japan
**Graduate School of Pharmaceutical Sciences, Tohoku University, Aobayama, Sendai 980-8578, Japan

An improved method for a suitable derivatization of polyhydroxylated steroids having one or two tert-hydroxyl groups at the 5β-, 14α-, 17α-, 24-, and/or 25-positions by capillary gas chromatography (CGC) is described. By using trimethylsilyl triflate as a silylating reagent and 2,6-lutidine as a catalyst, each of 5β-cholane and 5α-cholestane series of steroids was successfully transformed into trimethylsilyl (TMS) ether derivatives to give a single CGC peak under mild conditions. More bulky triethylsilyl (TES) etherification of 14α- and 17α-hydroxy compounds provided multiple CGC peaks arising from completely- and/or incompletely-derivatized TES ethers accompanied by their thermal elimination products.

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