Application of an ion-cluster technique to the analysis of endogenous hydroxylated compounds. I. Preparation of a doublet by use of a mixture of trimethylsilylimidazole (TSIM) and TSIM-d3.

In order to apply the intensity-matching technique to polyhydroxysteroids in biological fluids, the doublet of [M]+ and [M+3]+ was prepared in the process of derivatization by use of a mixture of trimethylsilylimidazole (TSIM) and TSIM-d3 and was used for mass fragmentography. The molar ratio of TSIM and TSIM-d3 was defined by the reciprocal of the number of hydroxyl groups in steroids. This technique may be useful in identifying low levels of the endogenous polyhydroxysteroids of interest in biological fluids.