Chiral separation of α-tocopherol and α-tocopheryl acetate by supercritical fluid chromatography for accurate vitamin E nutrition labeling

Abstract

Separations of respective stereoisomers of α-tocopherol and α-tocopheryl acetate by supercritical fluid chromatography (SFC) using polysaccharide-based chiral stationary phases (CSP) were studied. Two separate methods have been developed for α-tocopherol and α-tocopheryl acetate with total runtime of 35 min and 15 min, respectively. Under the optimized conditions, all-rac-α-tocopherol is separated into four peaks (peak area ratio 5:1:1:1) on an amylose tris(3,5-dimethylphenylcarbamate) CSP, and all-rac-α-tocopheryl acetate is separated into 2 peaks with equal peak areas on a cellulose tris(3,5-dimethylphenylcarbamate) CSP. The characteristic peak profiles of these racemic mixtures are distinctive enough to differentiate synthetic vitamin E (racemate) from the naturally occurring vitamin E (RRR-stereoisomer only). The α-tocopherol method has been demonstrated free of interference from other natural tocopherols, such as β-, γ-, and δ-tocopherol. Evaluation of the α-tocopherol method with commercially available vitamin E dietary supplements and an infant formula showed acceptable results in the qualitative analysis of α-tocopherol. These SFC methods provide fast, simple, and “green” solutions to verify or determine the type of vitamin E for dietary supplement and food manufacturers to ensure accurate vitamin E nutrition label claims.