[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.