SHAPE SELECTIVITY OF C-30 PHASES FOR RP-HPLC SEPARATION OF TOCOPHEROLISOMERS AND CORRELATION WITH MAS NMR DATA FROM SUSPENDED STATIONARY PHASES

Vitamin E (tocopherol) acts in various organisms as the main free radi cal scavenger, This capacity, which is enhanced by the synergetic effe ct of vitamin C and carotenes, points to a possible application as ant i-tumor agent in chemotherapy. There are several isomeric forms, namel y alpha-, beta-, gamma-, and delta-tocopherol, having different antiox idative abilities, with alpha-tocopherol being the most biologically a ctive, Using methanol as eluent and a C-30 stationary phase, we achiev ed complete separation of alpha-, beta-, gamma-, and delta-tocopherol and alpha-tocopherol acetate by RP-HPLC within 14 min, Detection was p erformed by UV and H-1 NMR spectroscopy, The advantage of NMR is the p ossibility of structural identification of chromatographic peaks. Also , coeluting peaks are easily recognized, The enhanced shape recognitio n of the C-30 phase has been attributed to the high order of the alkyl chains of the stationary phase, This has, so far, been proven by soli d-state NMR spectroscopy, We now introduce the technique of C-13 MAS N MR spectroscopy of suspended stationary phases. The resulting NMR spec tra reveal that, in the presence of weak eluents, like methanol, the o verall high order of the C-30 chains is slightly altered, whereas in s tronger elements, like MTBE, the alkyl chains possess a higher mobilit y.