GC-MS CHARACTERIZATION AND QUANTIFICATION OF STEROLS AND CHOLESTEROL OXIDATION-PRODUCTS

A GC-MS method has been studied for characterization and quantification of phytosterols, cholesterol and cholesterol oxidation products. Baseline separations have been achieved between cholesterol, cholesterol 5alpha-6alpha-epoxide, 5-cholestene-3beta-ol-7one (7-keto-cholesterol), cholestene-3beta-5alpha-6beta-triol, 5-cholestene-3beta-25-diol (25-hydroxycholesterol), 5-cholestene-3beta-20alpha-diol (20alpha-hydroxycholesterol), 5-cholestene-3beta-7beta-diol (7beta-hydroxycholesterol) and 5-cholestene-3beta-19-diol (19-hydroxycholesterol) as well as between alpha-cholestane, cholesterol, stigmasterol, campesterol and beta-sitosterol. Excellent linearity of response has been obtained permitting reliable quantification. The characterization of each derivatized sterol has been performed by mass-spectrometry. The results confirm the utility of combined gas chromatography-mass spectrometry in the analysis and characterization of sterols and cholesterol oxidation products.