COULOMETRIC DETECTION IN HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC ANALYSIS OF CHOLESTERYL ESTER HYDROPEROXIDES

A highly sensitive and simple method for the determination of choleste ryl ester hydroperoxides (ChE-OOH) was developed using high-performanc e liquid chromatography (HPLC) with coulometric electrochemical detect ion. The lowest detectable level by this technique was 2 pmol for chol esteryl linoleate hydroperoxides at the signal-to-noise ratio of 3. Th is method was applied to the determination of ChE-OOH presumably prese nt in human plasma. Although ChE-OOH could not be detected, the ChE-OO H level in the fluid was estimated to be less than 27 nM. It was found that the extraction efficiency of an internal standard, cholesteryl n ervonate, was decreased by lowering its amount spiked to the plasma. T he concentration of ChE-OOH in human plasma and plasma lipoprotein, wh ich were peroxidized with a radical initiator in vitro, could be deter mined by use of this standard. HPLC-coulometric technique is, therefor e, useful to measure the peroxidation of plasma lipids in vitro.