Separation of RRR-a-tocopherol by chiral chromatography

Abstract

Background: a-Tocopherol can exist as eight possible stereoisomers due to the presence of three chiral carbons. Regulations and industry guidelines necessitate that dietary vitamin E intakes be based on the vitamin E activity of RRR-a-tocopherol. Food products fortified with synthetic all-rac-a-tocopherol or all-rac-a-tocopheryl acetate during manufacturing will require chiral separation of the a-tocopherol stereoisomers for accurate estimation of vitamin E activity. Objective: The development of an HPLC method utilizing a chiral column for the chromatographic separation of RRR-a-tocopherol from other a-tocopherol stereoisomers. Method: Normal phase liquid chromatographic separation using a polysaccharide-based chiral column with fluorescence detection of a-tocopherol stereoisomers. Results: The described chromatographic method achieves baseline resolution of RRR-a-tocopherol from its stereoisomers. Method selectivity, precision, and robustness were evaluated and acceptable performance was achieved. Conclusions: The chromatographic method was found to be suitable for application where both RRR-a-tocopherol content and total a-tocopherol content are required for routine compliance testing. Highlights: A robust and precise chomatographic method for the baseline resolution of RRR-a-tocopherol from its stereoisomers was acheived.