Separation of steryl esters by reversed-phase liquid chromatography

Thirty steryl esters composed of ten different fatty acids and 14 sterols as well as two wax esters were analyzed by reversed-phase liquid chromatography on a Zorbax ODS column at 205 nm using acetonitrile-isopropanol 60:40 (v/v) as a mobile phase. Contributions (sigma values) of individual double bonds and alkyl groups in the steryl ester were determined from the relative retention values for steryl esters with and without the feature. A double bond and an alkyl group had a greater effect on the retention time of a steryl ester when present in the fatty acid rather than in the sterol moiety. The sigma value can be used to obtain structural information about a steryl ester. Separation of a complex mixture of steryl esters found in corn oil was achieved using this technique.