Abstract: A simultaneous determination of sinapic acid, quercetin and protocatechuic acid in Allium cepa Linn by capillary aone electrophoresis with electrochemical detection was reported. The parameters affecting the separation and detection such as detection potential, separation voltage and concentration of running buffer were evaluated. Under the optimum conditions, the analytes were baseline separated within 25 min in a borax buffer (PH=9.0). Good linear relationship was established between peak current and concentration of analytes in the range of 2.0×10^-7-1.0×10^-4g/mL for sinapic acid, 2.0×10^-7-5.0×10^-5g/mL for quercetin, and 5.0×10^-7-5.0×10 ^-5g/mL for protocatechuic acid. The detection limit (S/N=3) is 1.5×10^-7g/mL,1.6×10^-7g/mL and 3.6×10^-7g/mL respectively for these three analytes. This method has been used for the determination of active ingredients in allium cepa linn with satisfactory results.

Key words: electrochemical detection, sinapic acid, quercetin, protocatechuic acid, Allium cepa Linn, capillary zone electrophoresis, electrochemical detection, sinapic acid, quercetin, protocatechuic acid, Allium cepa Linn