Study Dynamics Of Tebuconazole Residues In Apple,Rice And Soil

Tebuconazole,(RS)-1-p-chlorophenyl-4,4-dimethyl-3-(1H-1,2,4-triazol-lylmethy1)pentan-3-ol, a kind of hydroxyethyl triazole derivatives, is a triazole systemic fungicide, and its toxicity classification is low-toxic fungicide. In this dissertation we studied the dynamic degradation of tebuconazole in apple, rice and the soil and water, and studied the final residue to evaluate the residual status and environment safety. The main research results of this study are given below.1.The study optimized the residue detection procedure of tebuconazole in apple and soil, and set up a method to analysis by gas chromatography-nitrogen phosphorus detector (GC/NPD).The soil sample soaked in acetone/acetic ester (1+1, v+v) and had an ultrasonic extraction,the apple sample had a slurry extraction instand, and then concentrated and quantified with ethyl acetate, and detected by GC/NPD at last. The average recoveries of tebuconazole with various fortified concentration in the apple and soil samples were81.0%～104%, relative standard deviations (RSD) were1.34%～6.20%respectively.2.Optimized the instrument condition of gas chromatography-mass spectrometry (GC/MS), and set up an analysis method to qualitative and quantitative tebuconazole in brown rice, rice hull, water and soil.tebuconazole in water samples extracted by acetonitrile, followed by a dehydration, concentrated nearly dry and then quantified with acetone,and detected by GC/MS at last. tebuconazole in the Plant, brown rice, rice hull and soil samples extracted by acetone/acetic ester (1+1,v+v), followed by salting out, purification through alumina chromatography column, concentrated nearly dry and then quantified with acetone,and detected by GC/MS at last. The average recoveries of tebuconazole with various fortified concentration in the plant, brown rice, rice hull, soil and water samples were81.0%～104%, relative standard deviations (RSD) were1.34%～6.20%respectively.3.After detected and analysis the two different kinds of pesticide trial, some certain degradation rules of tebuconazole were found in apple and soil. The degradations of tebuconazole in apple and soil were in accordance with the first order dynamic equation. The half-lifes were4.6-20.7days in apple and10.5-25.5days in soil, which average were12.8and15.6respectively.4.The degradations of tebuconazole in rice plant, soil and water were aslo in accordance with the first order dynamic equation,which half-lifes were3.4～20.0days,8.1～26.6days and4.1～13.1days, respectively.5.Through the detection, it was conclude that the final residue of tebuconazole in apple, rice and soil has relationship with the dose of the spraying, spraying times and sampling interval time.It increased with the increasing dose of the spraying and spraying times, but decreased with the increasing sampling interval time. The study suggest as followed.25%tebuconazole wettable powder applied in apple should have a1500～2000times dilution, which dosage of effective composition is about167～125mg/kg, spray3times, and the spraying interval is7days while the safety interval is21days.65%tebuconazole-c’s zinc wettable powder applied in apple should have a900～1500times dilution, which dosage of effective composition is about433～722mg/kg, spray3times, and the spraying interval is10days while the safety interval is21days.30%validamycin-tebuconazole (validamycin4%, tebuconazole26%) suspending agent applied in rice which spraying dosage of effective composition should be67.5-90g/hm2, spray2times, and the spraying interval is7days while the safety interval is35days. On this condition, the final residual of tebuconazole in the two plants can satisfy the existing Maximum Residue Limit(MRL) of our country.