Determination of alpha-tocopherol stereoisomers in biological specimens using chiral phase high-performance liquid chromatography.

The alpha-tocopherol stereoisomers in biological specimens were investigated using high-performance liquid chromatography. All-rac-alpha-Toc acetate was separated into four peaks (peak area ratio: 4:2:1:1) by Chiralpak OP(+)HPLC. 2R-isomers constituted the first peak and 2S-isomers were separated into three peaks (peak area ratio: 2:1:1). 2-Ambo-alpha-Toc acetate was completely separated into RRR- and SRR-alpha-Toc acetate by this method. The present HPLC method was used for the separation of all-rac-alpha-Toc in blood and tissues of rat. The analytical recoveries of RRR- and SRR-alpha-Toc acetate added to blood and tissues were 90.5-98.2% for RRR-alpha-Toc and 93.7-100.5% for SRR-alpha-Toc. The distribution of alpha-Toc stereoisomers in the blood and tissues from rats administered all-rac-alpha-Toc acetate was investigated by HPLC. The concentrations of the 2R-isomers in the blood and tissues were markedly higher than the concentrations of the 2S-isomers, and the levels of alpha-Toc stereoisomers showed marked differences between blood and tissues.