Submitted to: Journal of Chromatography
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/26/2000
Publication Date: N/A
Interpretive Summary: Vitamin E and related compounds are important minor constituents of oilseeds. They provide many health benefits and are useful in oil preservation. State-of-the-art techniques are needed for studying the impact of the minor constituents on the quality and stability of vegetable oils. Separations of the vitamin-E active compounds in edible oils were evaluated by capillary electrochromatography. The new high-speed techniqu requires minimum solvent consumption. The technique can be used by seed growers and the food/oil industries for information on factors affecting oil quality/stability. Food scientists can utilize the optimized distribution data for improving food flavor and quality.
Technical Abstract: Separations of lipid antioxidants, tocopherols (T), and tocotrienols (T3) on octylsilica (OS), octadecylsilica (ODS), phenylsilica, or silica were studied by capillary electrochromatography (CEC)-UV detection. The homologues and isomers of the vitamin E-active compounds were best separated with an OS column. CEC with an ODS column tended to yield broad peaks with poor resolution. Among the various mobile phases evaluated, [acetonitrile-methanol(64:36)]-[25 mM tris(hydroxymethyl)aminomethane/pH 8](95:5) eluent systems produced the most satisfactory results. Under these conditions, a base-line separation of an 11-component mixture was obtained with elution order similar to that observed in reversed-phase HPLC: delta T3 > (gamma+beta)T3 > alpha T3 > epsilon T > (delta+zeta)T > (gamma+beta)T > alpha T > alpha T-acetate. CEC of the antioxidant acetates led to separations inferior to those of the parent compounds. Effects of CEC experimental variables (e.g. mobile phase solvents and buffers, stationary phases, and electric field) on analyte separations were assessed in the context of separation factors and capacity factors.