DETERMINATION OF ACTIVE INGREDIENTS OF PHYLLANTHUS URINARIA BY CAPILLARY ELECTROPHORESIS WITH AMPEROMETRIC DETECTION

A method based on capillary electrophoresis with amperometric detection was developed for the separation and determination of rutin, quercetin, ferulic acid, caffeic acid, and gallic acid in Phyllanthus urinaria. The effects of the acidity and the concentration of the running buffer, separation voltage, injection time, and detection potential were investigated to acquire the optimum conditions. The detection electrode was a 90-mu m diameter platinum microelectrode at a detection potential of +1.00 V (versus Ag/AgCl). The five analytes could be well separated within 27 min in a 50 cm length fused-silica capillary at a separation voltage of 15 kV in a 10 mmol/l borate buffer (pH 9.0). The response was linear over about three orders of magnitude with detection limits (S/N = 3) ranging from 0.4 mu M to 5.9 mu M for all the analytes. The proposed method was successfully applied to the analysis of active ingredients in Phyllanthus urinaria with satisfactory assay results.