Separation of RRR-α-Tocopherol by Chiral Chromatography

Background: alpha-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-alpha-tocopherol. Food products fortified with synthetic all-rac-alpha-tocopherol or all-rac-alpha-tocopheryl acetate during manufacturing will require chiral separation of the alpha-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-alpha-tocopherol from other alpha-tocopherol stereoisomers. Method: Normal phase liquid chromatographic separation using a polysaccharide-based chiral column with fluorescence detection of alpha-tocopherol stereoisomers. Results: The described chromatographic method achieves baseline resolution of RRR-alpha-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-alpha-tocopherol content and total alpha-tocopherol content are required for routine compliance testing. Highlights: A robust and precise chomatographic method for the baseline resolution of RRR-alpha-tocopherol from its stereoisomers was acheived.