title: Automated high-performance liquid chromatographic method with precolumn reduction for the determination of ubiquinol and ubiquinone in human plasma.
abstract: We developed a gradient HPLC method with automated precolumn reduction for direct electrochemical detection of ubiquinol-10 (CoQ10H2) and total coenzyme Q10 (TQ10) in human plasma. The concentration of ubiquinone-10 (CoQ10) was calculated by subtraction of CoQ10H2 from TQ10. Preparation of reducing agent and precolumn reduction was performed by a programmable auto-injector. The two mobile phases used were: A, 100% of methanol containing 50 mM sodium perchlorate and 10 mM perchloric acid; and B, a mixture of ethanol and tert.-butanol (80:20, v/v). Sample preparation was simply a deproteinisation process with 10-fold ethanol. A good linear relationship was obtained for CoQ10H2 concentration from 0.1 to 3 micromol/l. The detection limit was 2.5 nmol/l with an injection volume of 20 microl. The analytical recovery and reproduciblity were generally >90%. To validate the method, 18 freshly collected plasma samples of normal healthy subjects were analysed. The mean ratio of CoQ10H2/CoQ10 was 93:7. The proposed method is sensitive, reliable and can be used for clinical investigation.
authors.affiliation: School of Public Health, Beijing Medical University, People's Republic of China.
authors.forename: Q
authors.initials: Q
authors.lastname: Wang
authors.forename: B L
authors.initials: BL
authors.lastname: Lee
authors.forename: C N
authors.initials: CN
authors.lastname: Ong
mesh_terms: D001331:Automation; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003067:Coenzymes; D006801:Humans; D012016:Reference Values; D015203:Reproducibility of Results; D014451:Ubiquinone / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D003067:Coenzymes; D014451:Ubiquinone; C024989:coenzyme Q10; C003741:ubiquinol