Abstract:

High performance capillary electrophoresis (CE) with electrochemical detection (ECD) was employed to determine the amount of hydroxyl radical in CuSO4-vitamin C reaction system (pH 7.4). The effects of some important factors, such as the acidity of the running buffer, separation voltage, injection time and the potential applied to the working electrode were investigated to choose the CE-ECD optimum conditions. The reaction system to produce hydroxyl radical was also optimized such as the effects of reactant concentration and reaction time on the concentration of 3,4-dihydroxy-benzoic acid. Operated in a wall-jet configuration, a 300 μm diameter carbon-disc electrode was used as the working electrode. Excellent linearity was obtained in the concentration ranging from 1.5×10-4 mol/L to 6.0×10-6 mol/L for the reaction product. The detection limit was 1.5×10-6 mol/L (S/N=3). This method was successfully applied to determine scavenging activities of Chrysanthemum for hydroxyl radical.

Key words: Chrysanthemum , electrochemical detection (ECD), hydroxyl radical, in CuSO4-vitamin C reaction system, scavenging activity, capillary electrophoresis (CE)