Electrocatalytic determination of dithiocarbamate-based pesticides using electrodes modified with metal phthalocyanines

An electrocatalytic method has been proposed for determining dithiocarbamat e-based pesticides (carbathion, nabam, ferbam, thiram, and thiuram) using a carbon-paste electrode modified with iron(II) and cobalt(II) phthalocyanin es. The first wave of carbathion oxidation in both aqueous and organic solu tions does not change compared to an unmodified carbon-paste electrode; for the second stage of oxidation, a decrease by 100 mV in the overpotential a nd a significant increase in the current are observed. The electrochemical signal is observed in the range of potentials characteristic for the oxidat ion of metal phthalocyanines, and (fie metal phthalocyanine serves as the e lectron carrier. A similar effect is observed for the electrochemical oxida tion of nabam. The catalytic activity of the metal phthalocyanines to ferba m, thiram, and thiuram in acetone has been determined. In the case of the e lectrochemical oxidation of ziram and zineb, the electrocatalytic effect is not observed. The dependence of the peak current on the pesticide concentr ation is linear within the range from 1 x 10(-3) to 1 X 10(-7) M. The adsor ption preconcentration of pesticides decreases the limit of detection by an order of magnitude.