Electrochemical Study of the Pesticide Methidathion at a Mercury Electrode Under Cathodic Stripping Mode

Methidathion, a non-systemic organophosphorous insecticide and acaricide is studied at the hanging mercury drop electrode under cathodic stripping mode by means of cyclic and square-wave voltammetry (SWV). Its electrode reaction is analyzed in the light of recent theory of cathodic stripping processes of insoluble salts of SWV. Its complex electrode mechanism is described by an electrode reaction of a second order, complicated by adsorption of methidathion molecules on the electrode surface involving lateral interactions between each other. Moreover, under specific experimental conditions the electrode mechanism can be additionally complicated by multilayer formation on the electrode surface, as well as by a chemical transformation following the cathodic stripping process of the methidathion-mercury salt. Following the mechanistic study of the electrode reaction, a method for quantitative determination of methidathion is proposed applying SWV.