Rapid Separation of Free Sterols in Edible Oils by On-Line Coupled Reversed Phase Liquid Chromatography−Gas Chromatography

A rapid analysis of the sterol fraction of oils by on-line reversed phase liquid chromatography−gas chromatography (LC−GC) is described. Methanol:water is used as eluent in the LC preseparation step, 2000 μL/min being the speed of sample transfer. A programmed temperature vaporizer is used as an interface for the LC−GC equipment, and the solvent elimination is performed simultaneously in both the evaporative and nonevaporative modes so that a 3000-μL LC fraction can be transferred into the GC. The proposed procedure only demands previous dilution of the oil sample with CH 2 Cl 2 and allows the analysis of the sterol fraction in only 20 min, including the oil sample preparation and the LC−GC analysis itself. Keywords: Reversed phase LC−GC; on-line coupling; sterols; direct injection; edible oils