Determination of Quercetin by Dual-wavelength Overlapping Spectrophotometry

An UV-spectrophotometric method for the determination of quercetin was reported.In a B-R buffer medium of pH=7.45,two absorption peaks at the wavelength of 256 nm and 368 nm were observed,and the sum of absorbance at these two peaks showed good linearity with quercetin concentration in the range of 0.84～42.0 μg\5mL-1.The apparent molar absorptivity was 4.24×104 L\5mol-1\5cm-1 which was 86.8% higher than that obtained under the conventional single wavelength measurement mode.Detection limit of the proposed method was found to be 0.30 μg\5mL-1.The method was applied to the determination of quercetin in Jiangzhining capsules.The relative standard deviation of results was no more than 3.23%,and the values of recovery test obtained by the standard addition method were in the range of 95.2%～102.7%.