Determination of Isoniazid Using a Gold Electrode by Differential Pulse Voltammetry

Compared with the present electrochemical method of determining isoniazid (INH) content by polarography using a hanging mercury electrode, using a gold electrode for determination of isoniazid as proposed by this paper has substantial advantages of convenience, sensitivity, and no pollution. An irreversible anodic peak at ca. −0.3V vs SCE of INH in 0.5 M NaOH was used for quantitative determination of INH by cyclic voltammetry (CV) or differential pulse voltammetry (DPV). The peak current showed a linear dependence with INH concentration over the range 2.0×10−6–2.3×10−4 M by DPV with the detection limit of 9.69×10−8 mol/L. The proposed procedure was successfully applied to the assay of isoniazid tablets. The potential range of CV scan, pH, accumulation potential, accumulation time, interference, and possible response mechanism are also discussed.