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United States Department of Agriculture

Agricultural Research Service

Title: Capillary Electrochromatography of Phytosterols in Vegetable Oils

Authors
item Abidi, Sharon
item Rennick, Kathy

Submitted to: International Symposium on High Performance Liquid Phase Separations
Publication Type: Abstract Only
Publication Acceptance Date: June 7, 2002
Publication Date: March 1, 2003
Citation: ABIDI, S.L., RENNICK, K.A. CAPILLARY ELECTROCHROMATOGRAPHY OF PHYTOSTEROLS IN VEGETABLE OILS. INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE LIQUID PHASE SEPARATIONS. 2003. Abstracts. p.79.

Technical Abstract: Plant sterols are important neutraceutical constituents of vegetable oils. They are a class of compounds derived from 3-hydroxylated polycylic isopentanoids. Their structural varieties and compositional distributions are known to have significant bearing on oil quality and stability. Because of structural complexity and similarity, chromatographic isolation and separations of individual components of these bioactive substances have met with challenges. We wish to report a new capillary electrochromatography(CEC)-photodiode array detection (PAD) technique for the evaluation of plant sterols in high-oryzanol rice bran oil, dewax-rice bran oil, soybean oil, and other edible oils. The oil samples were purified by saponification(free sterols) and solid phase extraction(steryl esters) followed by thin layer chromatography. Aliquot analytical samples were chromatographed onto each of 3 um capillary columns(25 cm x 75 um I.D.) packed with short-chain, long chain alkylsilica(AS) or pentafluorophenylsilica. The sterols were eluted with a series of binary and ternary solvent systems. Among the mobile phases evaluated, acetonitrile-tetrahydrofuran-TRIS buffers provided the best results. The detector was set at 330 nm for steryl esters, e.g. gamma-oryzanols and 200 nm for sterols. Sterol separations depended largely on lengths of short-chain AS columns. Long-chain AS phases exhibited exceptional selectivity for closely related structures and their monomeric and polymeric packings had dramatic influence on component separations. The elution sequence appeared to be dictated by analyte side-chain structures. The CEC-PAD composition data were correlated with frying performance of selected vegetable oils.

Last Modified: 11/26/2014
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