A relatively rapid procedure is described for the spectrophotometric determination of total
tocopherol in red blood cells (RBC) based on a modification of the original Emmerie-Engel reaction. The critical feature in this method is the presence of a large amount of an added
antioxidant,
pyrogallol or
ascorbic acid, during the saponification and extraction stages and the use of thin-layer chromatography for
tocopherol purification. The total
tocopherol levels of plasma and erythrocytes were determined for a number of human subjects, for patients with
abetalipoproteinemia, and for rats. It was found that these levels had a wide range in normal human subjects but that the ratio of RBC to plasma
tocopherol was relatively constant and equal to 0.18, uncorrected, and 0.21 when both RBC and plasma values were corrected to 100% recovery. The RBC-to-plasma ratio for rats was 0.39. The accuracy of this ratio determined by the spectrophotometric procedure was verified by measuring the distribution of [(14)C]
tocopherol in RBC and plasma when radioactive
vitamin E was introduced into the blood by both in vitro and in vivo techniques. The addition of radioactive
tocopherol to RBC or plasma at the initial stage of the analysis permits an accurate determination of the total
tocopherol in RBC or plasma by calculations based on the recovery of the added
isotope. This procedure for erythrocyte
tocopherol analysis is compared with a gas-liquid chromatographic method in current use.