[31] High-performance liquid chromatography-coulometric electrochemical detection of ubiquinol 10, ubiquinone 10, carotenoids, and tocopherols in neonatal plasma

This chapter describes a method that combines high-performance liquid chromatography (HPLC) with coulometric electrochemical detection and individual internal standardization. HPLC with coulometric electrochemical detection is characterized by total oxidation or reduction of the substance passing the electrode. A micromethod for the rapid simultaneous determination of several lipophilic antioxidants in plasma from newborn infants is also presented in the chapter. Because only 5μl of plasma is required, the procedure lends itself for repetitive use in very immature infants at risk for developing so-called oxygen radical diseases of the premature. The method allows continuous monitoring of antioxidants in patients and can easily be combined with monitoring other parameters of interest. Reuse of blood samples taken routinely for the determination of hematocrit and bilirubin concentration is possible, reducing the blood volume required to be taken for the oxygen radical-related studies to virtually zero. The chapter concludes with a discussion of the quantitation of lipophilic antioxidants.