Quantitative analysis of flavonoids and phenolic acid in Coreopsis tinctoria Nutt. by capillary zone electrophoresis

Capillary zone electrophoresis was developed for the simultaneous determination of five flavonoids and one phenolic acid, including taxifolin-7-O-glucoside, flavanomarein, quercetagetin-7-O-glucoside, okanin 4'-O-glucoside, okanin, and chlorogenic acid, in different parts and origins of Coreopsis tinctoria and its related species. Effects of acidity, running-buffer concentration, and modifier concentration were investigated to determine the optimum conditions for analyte determination. Analysis was performed within 18 min by using 50 mM borax buffer containing 15% acetonitrile as a modifier (pH 9.0) at 25 kV and 25°C. Hyperoside was used as internal standard for quantification. The method was accurate, simple, and repeatable, and was successfully applied to the analysis in 13 samples with satisfactory assay results. Results showed that C. tinctoria obviously differed from the related flower tea materials, "Hangju" and "Gongju". The parts (flowers, buds, seeds, stems, and leaves) of C. tinctoria also varied among one another. This study can serve as a foundation for the quality control and pharmacological evaluation of different parts of C. tinctoria and its related species.