Determination of Hydroxyl Radical in CuSO4-Vitamin C Reaction System Using Capillary Electrophoresis with Electrochemical Detection and Its Application in the Determination of the Scavenging Activities of Chrysanthemum

The hydroxyl radical in the CuSO4-vitamin C reaction (pH 7.4) system was determined using high-performance capillary electrophoresis (CE) with electrochemical detection (ECD). The effects of pH of running buffer, separation voltage, injection time, and the potential applied on the working electrode were investigated to optimize the CE-ECD conditions. The effects of concentration of reactants and reaction time on the concentration of reaction product, 3,4-dihydroxyl benzoic acid, were also discussed. A carbon-disc electrode (300 μm, diameter) was applied as the working electrode with the potential of 0.95 V to the reference electrode, saturated calomel electrode (SCE). Good linearity was obtained in the concentration range of 1.5 × 10−4.–6.0 × 10−6 mol/L for the reaction product. The detection limit (S/N = 3) was 1.5 × 10−6 mol/L. This method was successfully applied to determine the scavenging activities of Chrysanthemum.