RAPID SEPARATION OF FREE STEROLS IN EDIBLE OILS BY ONLINE COUPLED REVERSED-PHASE LIQUID-CHROMATOGRAPHY GAS-CHROMATOGRAPHY

A rapid analysis of the sterol fraction of oils by on-line reversed ph ase liquid chromatography-gas chromatography (LC-GC) is described. Met hanol:water is used as eluent in the LC preseparation step, 2000 mu L/ min being the speed of sample transfer. A programmed temperature vapor izer is used as an interface for the LC-GC equipment, and the solvent elimination is performed simultaneously in both the evaporative and no nevaporative modes so that a 3000-mu L LC fraction can be transferred into the GC. The proposed procedure only demands previous dilution of the oil sample with CH2Cl2 and allows the analysis of the sterol fract ion in only 20 min, including the oil sample preparation and the LC-GC analysis itself.