Study of Electrocatalytic Oxidation of Isoniazid Drug Using Alizarin Red S as A Mediator on the Glassy Carbon Electrode

The anodic oxidation of isoniazid (INH) has been studied on the glassy carbon electrode by electrocatalytic effect of Alizarin Red S (ARS) as a homogenous mediator in phosphate buffer (pH = 6). The linear sweep voltammetry (LSV) studies showed that the catalytic current of this system depends on the concentration of INH. The magnitude of the peak current for ARS increased severely in the presence of INH, and proportional to the concentration of INH. The obtained catalytic peak current was linearly dependent on the INH concentration in the range of 10-800 µmol L-1 and the detection limit of 3.94 µmol L-1 by LSV and in the range of 0.05-0.85 µmol L-1 and the detection limit of 0.0163 µmol L-1 by differential pulse voltammetry (DPV). The method also was used for estimation of the catalytic rate constant at catalytic reaction between ARS and INH. The influences of potentially interfering substances on the current response of the system were examined. The importance of the technique is because of its ability to electrocatalytic determination of INH with ARS as homogenous electrocatalyst, while it does not need to be prepared as for the modified electrode. The method was successfully applied for analysis of INH in solid pharmaceutical formulations