Capillary gas-liquid chromatography of faecal free and esterified neutral sterols

A method is described for the analysis of faecal free and esterified neutral sterols by high-resolution capillary gas-liquid chromatography (GC). After homogenization and filtration of the sample, free and esterified sterols are separated by reversed-phase Lipidex-5000 chromatography. The esterified sterols are saponified and analysed by GC. The free sterols are further fractionated on a Lipidex-5000 straight-phase column into oxo- and hydroxysterols, respectively. The GC separation of the compounds is achieved with an SE-30 open-tubular silica capillary column. The mean recoveries of the authentic sterols are 90.0% +/- 5.8% (SD) and the mean within-assay coefficients of variations are 3.7% +/- 2.9% (SD). The method permits determination of (A) the main animal sterols (cholesterol, coprostanol, epicoprostanol, cholestanol, coprostanone and cholestanone), (B) the amount of total plant sterols (beta-sitosterol, campesterol, stigmasterol and their metabolic conversion products) and (C) the degree of esterification of neutral sterols. In addition results obtained in faecal samples from eight healthy young men eating normal Finnish food are presented.