Degradation dynamics and residue analysis of ethoprophos in rice plant.

Degradation dynamics and terminal residue of ethoprophos of 10% ethoprophos GR in rice plant in Guangdong Province and Hubei Province in 2006 were investigated by gas chromatography.The results showed that the recoveries of ethoprophos from rice plant,rice grain and rice bran were 82.60%～92.24%,83.29%～91.60% and 83.74%～90.57%,respectively.The degradation dynamic equations of ethoprophos in rice plant were based on the first-order reaction dynamic equations.The half-life periods of degradation of ethoprophos were 6.01 d and 5.91 d in rice plant in Guangdong Province and Hubei Province,respectively.Ethoprophos was not detected in rice plant in Guangdong Province and Hubei Province after using 10% ethoprophos GR with dosages of 1800 g/hm2(a.i.) and 2 700 g /hm2(a.i.).The final residues of ethoprophos in the rice grain in Guangdong Province and Hubei Province were 0.0047 and 0.0041 mg/kg after using 10% ethoprophos GR with dosage of 2700 g/hm2(a.i.),while ethoprophos was not detected in rice grain in Guangdong Province and Hubei Province after using of 10% ethoprophos GR with a dosage of 1800 g/hm2(a.i.).Ethoprophos was not detected in rice bran in Guangdong Province after using 10% ethoprophos GR with dosages of 1 800 g/hm2(a.i.) and 2 700 g/hm2(a.i.),while the final residuce of ethoprophos in rice bran in Hubei Province after using 10% ethoprophos GR with a dosage of 2 700 g/hm2(a.i.) and ethoprophos was not detected in rice bran in Hubei Province after using 10% ethoprophos GR with a dosage of 1 800 g/hm2(a.i.).