The catalytic polarographic pre-wave of nickel(II) induced by 2-methylbenzimidazole

Abstract

A comprehensive study of the prewave of NiII induced by 2-methylbenzimidazole in sodium barbital/nitric acid/potassium sulfate media was carried out by using various polarographic techniques in order to establish the mechanism via which the underlying electrode reaction proceeds. Based in the proposed mechanism, the formation of the catalytic complexes is a surface process involving deprotonated 2-methylbenzimidazole; the adsorption of this compound over the catalyst concentration where the prewaves are well-defined conforms to a Langmuir isotherm. Accordingly, a plot of the reciprocal of the limiting current for the prewave against the reciprocal of the ligand-catalyst concentration is a straight line. This finding was exploited for the determination of 2-methylbenzimidazole at concentrations from 5 × 10−7 to 5 × 10−5 M from NiII prepeaks recorded by differential pulse polarography and square-wave voltammetry