The fractionation of cholesterol esters by silicic acid chromatography.

Within recent years, the technique of silicic acid chromatography to separate complex mixtures of lipides has been developed widely (1-3). At the present time it is possible to resolve some eight different classes of lipides ranging from hydrocarbons to phospholipides on a single column (4). In addition, this procedure has been used to separate classes of phospholipides from one another (5). Our particular interest in the cholesterol ester fraction (6, 7) has led us to investigate the resolution of individual cholesterol esters by this means, and a method for obtaining four major categories has been developed. The technique compares favorably with destructive methods of analysis (i.e. ester hydrolysis and analysis of fatty acid components) while preserving the intact ester. Its application to model compounds and biological mixtures is illustrated.