A pulse polarographic method for the analysis of zinc dithiocarbamates

An extremely sensitive pulse polarographic method for the determination of zinc dimethyldithiocarbamate (an agricultural fungicide) and zinc di-n-pentyldithiocarbamate (a petroleum additive), has been developed based on the reaction of their dithiocarbamate moiety with copper(II) perchlorate in acetonitrile medium. Well defined diffusion-controlled peaks are observed at –140 mV and –130 mV (vs SCE) for zinc dimethyldithiocarbamate and zinc di-n-pentyldithiocarbamate respectively. The peaks shows approximately four-fold higher sensitivity than that obtained by pulse polarography of the zinc dithiocarbamate alone. A linear relationship is obtained between concentration of the zinc dithiocarbamate [added to copper(II)] and peak current. Using cyclic voltammetry, a probable mechanism for the zinc dithiocarbamate-copper(II) reaction has been proposed.