Validation and application of an HPLC-EC method for analysis of coenzyme Q10 in blood platelets

Previous studies have indicated that analysis of coenzyme Q10 (CoQ10) in platelets may be clinically useful. The study objectives are to describe, validate and provide application of an HPLC-EC method for platelet CoQ10 analysis. This method analyzes oxidized (ubiquinone-10) and reduced (ubiquinol-10) forms of CoQ10 using two separate injections with the electrochemical analytical cell set at neutral and oxidizing potentials. Results showed that chromatograms were free of interfering peaks. Calibration curves were constructed over a concentration range 116-2317 nmol/L (r(2) = 0.99). The extraction recovery was >95%. The within-run precision CV% was < or =4.2%, and the day-to-day precision was < or =9.9%. Platelets were isolated by differential centrifugation, and frozen at -70 degrees C until analysis. The application of the method was used to compare accumulation of CoQ10 in platelets vs plasma in eight adult volunteers during a 28 day supplementation period (5 mg/kg/day of ubiquinol-10). Mean platelet total CoQ10 was 164 pmol/10(9) cells, and ubiquinol-10:total CoQ10 ratio was 0.56. During supplementation platelet CoQ10 levels were more consistent and predictable than plasma CoQ10 levels. The results indicate that this validated method for platelet ubiquinol-10 and ubiquinone-10 analysis is acceptable for use in the clinical laboratory, and that platelet CoQ10 may have important advantages over plasma during CoQ10 supplementation.