[Measurement of vitamin E from biological samples]

Recent advances in HPLC have enabled to measure small amounts of tocopherols in biological samples. A fluorescence detector is usually used for detection of tocopherols, however we have determined tocopherols of blood samples by an electrochemical detection (ECD). This ECD method is 1,000 times more sensitive than conventional fluorescence methods, and is suitable for detection of small amounts of tocopherols of blood cells. In this report, preparation and extraction methods from blood samples are described. Preparation of blood to separate plasma, platelets, mononuclear cells, and polymorphonuclear cells is performed using a density-gradient method. Extraction of tocopherols usually involves saponification using ethanolic solution of potassium hydroxide.