Residues And Dissipation Dynamics Of Tebuconazole And Prochlorazin Rice Field

The residue analysis methods of tebuconazole and prochloraz in different rice matrices were established in this thesis.All samples were extracted by acetonitrile,then refined by PSA and Carb,finally detected by HPLC-FLD.The results showed that when the spiked levels ranged from 0.2 to 5.0 mg/kg,the recoveries of tebuconazole in rice matrices was 74.5%?103.8%,the relative standard deviations was 1.07%?8.41%;the recoveries of prochloraz in rice matrices was 72.3%?108.3%,the relative standard deviations was 0.96%?8.19%.The limit of detection for this method was 1.0×10-9,and the limit of quantification for rice plants,rice hull,rice,soil and paddy water were 0.5 mg/kg,0.2 mg/kg,0.2 mg/kg,0.2 mg/kg and 0.2 mg/kg,respectively.These methods are easy to operate,the sensitivity and accuracy are all according with national standards and requirements for pesticide residue detection.Through by rice field trials in Hunan,Shandong and Guangxi province in 2014-2015,we studied the dissipation dynamics and final residues of the 45%tebuconazole·prochloraz EW in paddy field.The dissipation dynamics tests results showed that the degradation half-lives of tebuconazole in rice plants,paddy water and soil were 1.79?6.08d,1.56-2.08d and 4.85-8.25d,respectively;the degradation half-lives of prochloraz in rice plants,paddy water and soil were 0.54-3.03d,1.09-2.97d and 8.89-9.76d,respectively.All the degradation half-lives were less than 30d,so the tebuconazole and prochloraz were all belong to easily degradable pesticides.The final residues tests results showed that when the dosage of 45%tebuconazole*prochloraz EW was 236.25-354.3 75g.a.i/ha,applying 3-4 times,applying pesticide interval for 10 days,recovery intervals for 20 or 30d,the residues in all the rice samples in field trials were all less than the MRLs of tebuconazole and prochloraz.