毛细管电泳-电化学检测法测定硫酸铜-维生素C反应体系中的羟基自由基和菊花的抗氧化活性

采用毛细管电泳-电化学检测方法,以对羟基苯甲酸为自由基捕捉剂,测定了硫酸铜-维生素C反应体系(pH 7.4)中生成的羟基自由基。研究了电极电位、运行液的pH值、电泳电压及进样时间对体系中反应物和产物分离的影响,得到了最优化的测定条件;讨论了体系中各反应物浓度和反应时间对产物浓度的影响。以直径为300 μm的碳圆盘电极为检测电极,工作电极电位为0.95 V(vs.SCE),目标产物3,4-二羟基苯甲酸在1.5×10-4~6.0×10-6 mol/L范围内线性关系良好,检测限（S/N=3）为1.5×10-6 mol/L。应用该方法,研究测定了不同品种菊花的抗氧化活性。

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

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 microm diameter carbon-disc electrode was used as the working electrode. Excellent linearity was obtained in the concentration ranging from 1.5 x 10(-4) mol/L to 6.0 x 10(-6) mol/L for the reaction product. The detection limit was 1.5 x 10(-6) mol/L (S/N = 3). This method was successfully applied to determine scavenging activities of Chrysanthemum for hydroxyl radical.