[Direct determination of tocopherols in plant oils by high-performance liquid chromatography]

Isomeric tocopherols determine the oxidation stability of unsaturated lipids. Therefore, the stability of vegetable oils in the process of their treatment and storage could be evaluated by the tocopherol levels. High-performance liquid chromatography has been suggested for rapid (10-12 min) and selective assay of alpha-, beta-, gamma- and delta-tocopherols in various vegetable oils: soybean, cotton, sea buckthorn, sunflower and wheat germ oil, and in hydrogenated fat. The samples without preliminary saponification and extraction were dissolved in the eluent and introduced into the column. The assay was conducted both in imported ("Beckman" and "Kratos" firms) and in Soviet ("Milichrom") chromatographs which included a detector-spectrophotometer with wave-length 294 nm, a column with silica gel, an eluent--hexane with 1.5% isopropanol. The quantitative determination was conducted with the use of reference solutions of alpha-tocopherol. The tocopherol yield comprised 99.8%.