Capillary column gas–liquid chromatographic separation of Δ5-unsaturated and saturated phytosterols

Abstract

Diets consisting of food ingredients of both plant and animal origin contain a complex mixture of sterols in the lipid fraction. Analysis of these complex mixtures of sterols is generally accomplished by capillary column GC and GC–MS. A very low polarity liquid phase (methylsilicone) and medium polarity columns of various dimensions are used for the separation and quantitation of sterols. However, these columns may not be able to separate some of the sterols in the mixture. The objective of this study was to accomplish the complete separation of a complex mixture of sterols by GC. In order to achieve this objective, a fused-silica capillary column (14% cyanopropyl-phenyl-methylpolysiloxane) of low/medium polarity was used. Excellent separation of campesterol and campestanol, and sitosterol, sitostanol and Δ5-avenasterol was achieved. In addition to GC resolution, a few critical points for the analysis of sterols are presented.