[26] Separation of the eight stereoisomers of all-rac-α-tocopherol from tissues and plasma: Chiral phase high-performance liquid chromatography and capillary gas chromatography

Abstract

Publisher Summary This chapter introduces chiral phase high-performance liquid chromatography (HPLC) and capillary gas chromatography (GC). These methods are used to evaluate patterns of all α-tocopherol (TOH) stereoisomers in rat tissues and plasma after oral all -rac- α - TA c treatment. All separation steps are performed with α-T-ME derivatives—that is, only one α-TOH derivative is required. Chiralcel OD, a commercially available chiral high-performance liquid chromatography (HPLC) phase, is able to separate all four 2 R -α-T-ME stereoisomers individually from a peak containing the four 2S stereoisomers. The chiral phase HPLC method is developed with a Chiralpak OP(+) column, which separates all -rac- α - TA c into four peaks containing (all 2R), (SSS + SSR) , SRR , and SRS stereoisomers. Therefore, the system yields only limited information with regard to α-TOH stereoisomer distribution, whereas the combination of HPLC and GC methods permits the determination of all α-TOH stereoisomers individually. The GC–mass spectrometry (GC–MS) method is used to differentiate between R,R,R-α -TOH- d 6 and S,R,R-α- TOH- d 3 in rat tissues. It is not feasible to follow this experimental protocol for an evaluation of all -rac forms because it requires at least eight differently deuterated α-TAc stereoisomers and a very complex GC–MS setup to distinguish all individual stereoisomers.