聚亚甲基蓝修饰金电极对抗坏血酸电催化氧化及其电分析方法研究

Electrocatalytic oxidation of ascorbic acid at a polymethylene blue modified gold electrode and its electroche-mical determination

研究了亚甲基蓝（methylene blue，MB）聚合物膜修饰金电极（PMB／Au）的制备及其性质，通过电化学阻抗谱图对PMB／Au进行了表征，并对抗坏血酸（ascorbicacid，AA）在PMB／Au上的电化学行为进行了研究。结果表明，PMB／Au对从的氧化具有良好的电催化作用，使从的过电位降低约200mv，氧化峰电流明显增大。测得从在PMB／Au上的电荷转移系数为0．70，催化反应速率常数为5．99×10^3mol^-1·S^-1。用方波伏安法（SquareWaveVoltammetry，SWV）测得氧化峰电流与从浓度在2．0×10^-5～6．0×10^-3 mol／L范围内呈良好线性关系，检出限为1．0×10^-5mol／L。将PMB／Au应用于Vc片剂和Vc注射液中从的测定。

The preparation and electrochemical properties of a polymethylene blue （PMB） modified gold electrode （PMB/Au） were investigated by cyclic vohammetry and electrochemical impedance spectnma （EIS）, the electrochemical behaviors of AA at the PMB/Au were also studied. It is shown that the PMB/Au exhibits a significant catalytic effect toward the oxidation of ascorbic acid （AA）. The oxidation peak potential was shifted 200 mV negatively and the peak current increased greatly for AA at the PMB/Au than that at the bare gold electrode. The electron transfer coefficient and the reaction rate constant for catalytic oxidation of AA on the PMB/Au were evaluated as 0.70 and 5.99 × 10^3mo1^-1· L· s^-1. The catalytic oxidation peak current was linearly dependent on the AA concentration and a linear calibration curve was obtained in the concentration range of 2.0× 10^-5～6.0 ×10-3 mol/L with the correlation coefficient of 0.9989, and the detection limit of 1.0 ×10^-5 mol/L by square wave voltammetry （SWV）. The proposed method can be applied in the determination of AA content in pharmaceutical tablets and injection. The determination results are satisfactory.