Capillary Electrophoretic Determination of Kaempferol, Quercetin and Caffeic Acid in TCM Polygonum Aviculare

A method for the simultaneous separation and determination of kaempferol, quercetin and caffeic acid in the TCM, Polygonum aviculare by capillary electrophoresis was proposed. Mixed solution of 20 mmol·L-1 Na2B4O7-NaH2PO4 of pH 8.5 was used as the buffer solution, moving voltage of 20 kV and gravity injection time of 14 s were applied. UV-detection at the wavelength of 254 nm was adopted. The 3 analytes were completely separated within 7 min. Linearity ranges between 0.50-100 (for kaempferol), 0.70-146 (for quercetin) and 1.0-124 mg·L-1 (for caffeic acid) were obtained, with detection limits (3S/N) of 0.3, 0.4 and 0.6 mg·L-1 respectively. The proposed method was applied to the analysis of sample of Polygonum aviculare, giving values of recovery obtained by standard addition method in the range of 95.3%-106% with RSD′s (n=5) less than 3.5%.