Hydrolysis rate and In vitro anticholinesterase activity of fenitrothion and S‐methyl fenitrothion

Abstract Anticholinesterase activity in vitro of pure fenitrothion, S‐methyl fenitrothion (SMF) and mixtures of both was studied using different sources of cholinesterase. SMF was two to three orders as active an inhibitor as fenitrothion. In the mixtures, 1 and 5% SMF significantly influenced the I50 value of fenitrothion. The hydrolysis rates of both compounds are given. A method for the synthesis of pure SMF is also described.