碳糊电极阳极吸附伏安法测定大黄酸

在pH4.2的HAc-NaAc底液中,大黄酸在碳糊电极(CPE)上有一灵敏的吸附氧化峰,峰电位为1.14V(vs.SCE)。该氧化峰的二阶导数峰电流与大黄酸的浓度在8.0×10-9~8.0×10-7mol/L(富集120s)范围内呈良好的线性关系(r=0.998),检出限为2×10-9mol/L(S/N=3,富集180s)。探讨了大黄酸在CPE上的伏安性质和电极反应机理,并将本法应用于中药大黄中的大黄酸的测定,结果良好。

Determination of Trace Rhein at a Carbon Paste Electrode by Adsorption Voltammetry

The anodic adsorptive voltammetric determination of trace rhein was carried out at a carbon paste electrode.A sensitive adsorptive oxidation peak was yielded at 1.14 V(vs.SCE) in HAc-NaAc buffer solution.The second derivative peak current is directly proportional to the concentration of rhein in the range of 8.010~(-9)8.010~(-7) mol/L(r=0.998) for a 120 s accumulation.The detection limit is (2.0)10~(-9) mol/L(S/N=3).The proposed method was applied to the determination of rhein in Rheum officinale Baill with satisfactory results.The electrochemical behavior and the reaction mechanism of rhein at a carbon paste electrode were studied.