Selective determination of ubiquinone in human plasma by HPLC with chemiluminescence reaction based on the redox cycle of quinone.

Ubiquinone is an important biologically active compound in the living body. The determination of ubiquinone in human plasma is useful for the investigation of bioavailability of ubiquinone and for early diagnosis of several diseases. Therefore, we developed a high-performance liquid chromatography (HPLC) with chemiluminescence detection method for the analysis of ubiquinone in plasma samples. The method is based on luminol chemiluminescence detection of super oxide anion that is generated by the redox cycle reaction between ubiquinone and dithiothreitol. The HPLC system involved an octyl column with a mobile phase of methanol. Ubiquinone eluted from the column was mixed with dithiothreitol and luminol solutions simultaneously, and generated chemiluminescence was monitored by chemiluminescence detector. The calibration curve for standard ubiquinone solution was linear from 0.09 to 43.2 μg/mL (0.45-216 ng on column) with the correlation coefficient of 0.999, and the detection limit (S/N = 3) was 26 ng/mL (130 pg on column). Using the proposed HPLC method, the peak of ubiquinone in human plasma could be clearly detected on the chromatogram without any interference from plasma components.