Identification of metabolites of methylparathion in plant, water and soil

A CC-MS study was carried out to identify the decay products of methyl para thion in water, soil and rooted vegetable (radish) at different time interv als. The water (pH 5.5 and 8.0), soil (pH 7.5) and radish samples collected after the first half life shows the presence of O,O dimethyl O-p-nitro-2 o r 3-hydroxyphenyl phosphoorothioate which persists upto the 30th day in the alkaline water and soil samples. However, in acidic water methyl parathion is oxidized to give methylparaoxon. Radish samples show:the presence of two other products. These are identifie d as O,O-dimethyl o-p-aminophenyl -phosphoorothioate and O,O-dimethylo-p-hy droxyphenyl phosphoorothioate. The study indicates that the half life of me thyl parathion in different media is nearly the same but its metabolites ar e not identical.