39] Assay for blood plasma or serum

Abstract

Publisher Summary Because the amounts of lipid peroxides in the blood are rather small, a sensitive assay method is needed. For this purpose, the most appropriate among several reactions for detecting lipid peroxides is the thiobarbituric acid (TBA) reaction because of its sensitivity. TBA reaction with lipid peroxides gives a red-colored pigment. Malondialdehyde also gives the same product upon reaction with TBA. Because this product is fluorescent, a sensitive assay can be made by fluorometry. Results show that lipid peroxides can be measured by TBA reaction with fluorometry. Elimination of TBA-reacting substances other than lipid peroxides is necessary for the measurement of lipid peroxides in serum. The elimination procedure must be simple to avoid artifact due to the peroxidation during the procedure. One of the best procedures is to isolate lipids by precipitating them along with serum protein with the phosphotungstic acid–sulfuric acid system. By this procedure, water-soluble substances, which react with TBA to yield the same product as lipid peroxides, are removed. It was anticipated that platelet aggregation, if it occurs during the drawing of the blood, would liberate the TBA-reacting substances, and the effect of the aggregation was found to be eliminated by treatment with phosphotungstic acid–sulfuric acid system.