DETERMINATION OF A CHOLESTEROL OXIDE MIXTURE BY A SINGLE-RUN HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC ANALYSIS USING BENZOYLATION

A rapid, single-run high-performance liquid chromatographic method has been developed to separate and quantify benzoate esters of cholesterol oxides, providing high sensitivity via ultraviolet detection. The mobile phase was 85% isopropanol - water (v/v). Analyses of 7-ketocholesterol, cholestane-triol, epoxy-cholesterol, 7-hydroxycholesterol and 25-hydroxycholesterol were done using a 30 cm x 3.9 mm I.D. Novapak C18 column and a variable-wavelength ultraviolet detector (set at 230 nm). Linearity was excellent since a good correlation was observed. As low as 500 ng of cholesterol benzoate per 20-mu-l of solution can be detected by this method.