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Determination of Tocopherols and Tocotrienols in Foods and Tissues by High Performance Liquid Chromatography

1979; Marcel Dekker; Volume: 2; Issue: 3 Linguagem: Inglês

10.1080/01483917908060067

2331-0413

James N. Thompson, G. V. Hatina,

Antioxidant Activity and Oxidative Stress

Abstract Samples (10 g) of foods and tissues were homogenized in isopropanol and acetone. Low polarity lipids were obtained in the epiphase after the addition of hexane and water to the filtered extract. After separation, the hypophase was extracted twice with hexane and the combined epiphases were evaporated. The residue, which contained 97% of the vitamin E in the sample, was dissolved in hexane and aliquots (20 μl) were chromatographed on a 25 cm column of 5μ LiChrosorb Si60 with 0.2% isopropanol or 5% diethyl ether in moist hexane. A spectrofluorometer set at 290 nm excitation and 330 nm emission was used as a detector. Up to 2 mg lipid could be injected and 4 ng tocopherol produced a detectable peak. Four tocopherols (α, β, γ and δ) and three tocotrienols (α, β and γ) were measured in a variety of tissues and foods. Plastochromanol-8 and the antioxidant BHA were also detected in some samples. A preparative (1 cm diam) column was used to isolate tocotrienols from rubber latex and wheat flour and the purity and identify of the specimens, which were used as standards, were confirmed by mass spectroscopy. As esters of tocopherol are not fluorescent, foods containing added tocopheryl acetate were analysed after saponification.