Normal-phase high-performance liquid chromatography of tocopherols and tocotrienols - Comparison of different chromatographic columns

Natural vitamin E is composed of eight different vitamers (alpha-, beta-, g amma- and delta-tocolpherols and alpha-, beta-, gamma- and delta-tocotrieno ls), As these eight vitamers have different antioxidant and biological acti vities, it is necessary to have quantitative data on each substance separat ely. The aim of this study was to find universal HPLC columns for the separ ation of all eight components and to test if a few columns of the same mate rial (different batches) will give reproducible results. Normal-phase HPLC separations of vitamin E compounds in a prepared mixture (containing oat ex tracts, palm oil and tocopherol standards) were tried on six silica, three amino and one diol columns. As shown by calculations of retention factors ( k), separation factors (alpha), numbers of theoretical plates (N) and resol utions (R-s), the best separations were obtained on three silica columns an d two amino columns using 4 or 5% dioxane in hexane as the mobile phase as well as on a diol column using 4% tert.-butyl methyl ether in hexane as the mobile phase. (C) 2000 Elsevier Science B.V. All rights reserved.