REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC SEPARATIONS OFTOCOPHEROLS

The retention behavior and separation characteristics of five natural products alpha-, beta-, gamma-, delta-, and zeta(2)-tocopherols and th eir acetyl derivatives were studied by reversed-phase high-performance liquid chromatography (HPLC)-fluorescence detection. Investigated sta tionary phases included an octadecyl polyvinyl alcohol (ODPVA) column, several octadecylsilica (ODS) columns, and a pentafluorophenylsilica column. Mobile phases comprised methanol (or acetonitrile) and water a t variable proportions. Separation factors for beta- and gamma-tocophe rol isomers and capacity factors of the five tocopherols were determin ed under various conditions. The beta- and gamma-tocopherols were sepa rable on ODPVA but not on ODS. However, the beta-gamma pair was resolv ed with the latter column only as their ester derivatives. HPLC with m obile phases containing alkanols with carbon atoms greater than 2 favo red the separation of the beta-gamma pair on ODS and yielded results d iametrically different but complementary with those obtained with the ODPVA phase. The combined effects of mobile phases, stationary phases and antioxidant structures on component separations were delineated. ( C) 1997 Elsevier Science B.V.