Electroanalytical studies of the pesticides menazon and its hydrolysis products

An electroanalytical study based on d.c. polarography, differential pulse polarography (d.p.p.) and coulometry is described for Menazon, S-4, 6-diamino-1,3,5-triazin-2-yl)- methyl]-O,O-dimethylphosphorodithioate, and its alkaline hysdrolysis products in a (1 + 4) methanol/water medium. The responses of the different species are studied for analytical utility. Menazon itself produces two diffusion-controlled cathiodic waves or peaks at pH 4.78; the determination limit is 5.5 × 10^-7 M for the d.p. peak at about ?0.8 V vs. Ag/AgCl. The hydrolysis products obtained in 0.1 M sodium ydroxide give rise to four anodic waves. Acidification of the alkaline medium to pH 4.3 produces three well-defined waves; two cathodic and one anodic. The responses for the cathodic processes are linear with concentration over 2–2.5 orders of magnitude; the anodic wave is adsorption-controlled and provides linear response only at low concentrations. The detection limit for the hydrolysis products is 0.17 × 10^-6 M. Reaction mechanisms are proposed.