title: Identification and determination of active anthraquinones in Chinese teas by micellar electrokinetic capillary chromatography.
abstract: The simultaneous determination of emodin, aloe-emodin and rhein, in Semen Cassiae, Qinghai Wild Dahuang tea, Ningxia Juemingzi tea, Lanzhou Juemingzi tea and Surong Juemingzi tea, has been investigated by micellar electrokinetic capillary chromatography for the fi rst time. With an electrolyte containing 15 mm borax, 30 mm SDS, 10% (v/v) ethanol, at pH 9.60 and 20 kV applied voltage, the three analytes were completely separated within 12 min. The effects of the concentration of borax, electrolyte pH, the concentrations of SDS and organic modifier and the applied voltage on electropheoretic behavior and separation were studied. The linear calibration range was 4-120 micro g/mL (r = 0.9921) for emodin, 10-200 micro g/mL (r = 0.9970) for aloe-emodin and 2-100 micro g/mL (r = 0.9971) for rhein, respectively. Under the optimum conditions, the relative standard deviation (RSD) values (n = 6) of the migration time and the peak area of each peak was 0.59-0.80% and 1.30-3.22%, respectively. The contents of the analytes in Rheum, Qinghai Wild Dahuang tea, Semen Cassiae and three other kinds of teas were easily determined with recoveries ranging from 95.3 to 104.4%.
authors.affiliation: Department of Chemistry, Lanzhou University, Lanzhou, 730000, People's Republic of China.
authors.forename: Wenjie
authors.initials: W
authors.lastname: Zheng
authors.forename: Shufang
authors.initials: S
authors.lastname: Wang
authors.forename: Xingguo
authors.initials: X
authors.lastname: Chen
authors.forename: Zhide
authors.initials: Z
authors.lastname: Hu
mesh_terms: D000880:Anthraquinones / Q000032:analysis*; D001881:Borates / Q000737:chemistry; D002138:Calibration; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D004573:Electrolytes / Q000737:chemistry; D000431:Ethanol / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013662:Tea / Q000737:chemistry*
chemical_list: D000880:Anthraquinones; D001881:Borates; D004573:Electrolytes; D013662:Tea; C018851:borax; D012967:Sodium Dodecyl Sulfate; D000431:Ethanol