Sanz-Asensio_1997_Pest.Sci_50_187

A kinetic study of the hydrolysis of ethiofencarb (-ethylthio-o-tolyl methylcarbamate) in pure water and in aqueous solutions at pH 2, 6, 9 and 12 and at three different temperatures (4, 20 and 50(+/-1)degC) has been carried out using a gas chromatographic nitrogen-phosphorus detection method. The values of the first-order rate constants (k) for the degradation reaction were calculated. The values for k were found to be dependent on pH and temperature. No acid hydrolysis was observed in any case. Complete degradation of ethiofencarb was observed at pH 12 at all three temperatures; it was practically instantaneous at room temperature. Ethiofencarb was also completely degraded at pH 9 at 20 and 50degC, while in pure water (pH 6) degradation took place at 50degC but not at 20degC. Ethiofencarb was not degraded in pure water at lower temperatures and, due to the reversible nature of the reaction, at equilibrium about 80% of the pesticide remained undegraded at room temperature.