谷胱甘肽在10-甲基吩噻嗪修饰碳糊电极上的电催化氧化及电分析方法

研究了谷胱甘肽(还原型, glutathione, GSH)在10-甲基吩噻嗪(10-methylphenothiazine, MPT)修饰碳糊电极(MPT/CPE)上的电催化氧化行为。GSH在裸碳糊电极(carbon paste electrode， CPE)上的直接电化学氧化过程十分迟缓， 但在MPT/CPE上于0.702 V处出现一个不可逆氧化峰， 氧化电流大幅度增大。计时电流(chronoamperometry， CA)实验测得该电催化氧化反应速率常数k为(5.44±0.03)×10² (mol·L^-1)^-1·s^-1。用线性扫描伏安法(linear sweep voltammetry, LSV)测得催化氧化峰电流与GSH在5.0×10^-6～2.0×10^-3 mol·L^-1呈良好的线性关系， 线性回归方程I_pa=3.536c+2.117， r=0.999 0， 检测限为1.0×10^-6 mol·L^-1。同时用本方法对含GSH的市售药品进行了含量测定， 结果可靠。

Electrocatalytic oxidation of glutathione at 10-methylphenothiazine modified carbon paste electrode and its practical analytical application

The electrocatalytic oxidation of glutathione (reduced form GSH) at 10-methylphenothiazine (MPT) modified carbon paste electrode (MPT/CPE) was investigated by cyclic voltammetry (CV). Although GSH itself showed a very poor electrochemical response at carbon paste electrode (CPE), the response could be greatly enhanced by using MPT/CPE, which enables a sensitive electrochemical determination of the substrate GSH. The reaction rate constant for catalytic oxidation was evaluated as (5.44 +/- 0.03) x 10(2) (mol L(-1))(-1) s(-1) by using chronoamperometry (CA). The catalytic oxidation peak current of GSH versus its concentration had a good linear relationship in the concentration range of 5.0 x 10(-6) - 2.0 x 10(-3) mol L(-1) with the correlation coefficient of 0.9990, and the detection limit of 1.0 x 10(-6) mol L(-1) by linear sweep voltammetry (LSV). The method can be applied for the determination of GSH in injection samples with the satisfactory results.