A Versatile Detector for the Sensitive and Selective Measurement of Numerous Fat Soluble Vitamins and Antioxidants in Human Plasma and Plant Extracts

Fat-soluble vitamins (FSVs) play essential roles in a wide spectrum of physiological processes. One FSV, Vitamin E (tocopherol), along with a suite of other fat-soluble antioxidants (FSAs) (e.g., carotenoids, CoQ10) mitigate the potentially disastrous effects of oxidative stress linked to numerous diseases. These compounds are thought to exert their beneficial effects by acting as chain-breaking antioxidants, inhibiting lipid peroxidation of polyunsaturated fatty acids contained within biological membranes, thereby preventing the formation of potentially cytotoxic and highly reactive aldehydes (malondialdehyde and 4-hydroxynonenal). Although a number of FSVs and FSAs have been measured by HPLC-UV, this approach typically lacks the sensitivity and selectivity required to measure these compounds in biological samples. Electrochemical detection, however, is both sensitive and selective and makes use of the inherent redox activity of these compounds. The CoulArray® Coulometric Array Detector-the only HPLC electrochemical detector that is fully gradient compatible-uses an array of flow-through, highly efficient electrochemical sensors to generate qualitative, voltammetric data to help identify analytes and resolve co-eluting compounds. The versatility of this detector is illustrated using a variety of examples including: a global gradient method for determination of FSVs and FSAs in plasma; a gradient method for the analysis of carotenoid isomers in carrots; an isocratic method for the measurement of reactive nitrogen species damage to biomembranes measuring 5-nitro-gamma-tocopherol in rat astrocytes and human plasma; a gradient method for the measurement of tocopherol and tocotrienol isomers in palm oil; and an isocratic method for the determination reduced and oxidized CoQ9 and CoQ10 in human plasma.