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Studies on Degradation and Transformation of Pyrethroids in Apple

Author: DongQiang
Tutor: FanMingTao
School: Northwest University of Science and Technology
Course: Food processing and security
Keywords: Apple Pyrethrum insecticide Degradation Migration
CLC: TS255.7
Type: Master's thesis
Year: 2013
Downloads: 39
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Abstract


In apple production, the pyrethroid insecticides with moderate toxicity were largelyused to protect pests, which may cause Pesticide residues in fruit and soil. Pesticide in fruitsand soil has potential risks for human, environment and farm products. It is of importance tostudy the residues, the degradation and the migration of pyrethroid insecticides in Orchards.Fenpropathrin, Cypemethrin, Deltamethrin were chosen to do the study, they are extractedfrom apple, leaves and soil. The reasonable period time to stop spraying pesticides in applebefore harvest was put forward, which will ensure apple safety. The main results were asfollows:1. Rapid detection methods of pyrethroid pesticide residues was established. The Gaschromatograph method was used in this study to determine three pesticides of Fenpropathrin,Cypemethrin, and Deltamethrin from apple fruit, apple orchard soil and apple leaves.2. The extraction of the pesticides was done using SPE cartridge,0.1g activated carbonwas added to the acetonitrile column to remove the interfering materials leaves samples. Therecovery rate of three pesticides of Fenpropathrin, Cypemethrin, and Deltamethrin was95.9%to105.2%, and the relative standard deviations were all <6.7%. This method was convenient,accurate, and had a good separation effect and a high recovery, and it fully meet the challengeof pesticide residue analysis.3. Residue degradation of pyrethroid pesticides in apple garden was studied. In order tounderstand the residual contamination and the degradation rule of pyrethroid pesticides inapple production. The Gas chromatograph method was used in this study to determine threepesticides of Fenpropathrin, Cypemethrin, and Deltamethrin from apple dynamically. Theresults show that: In process of time, the contents of three pesticides were on a decliningcurve, and the size order registered as Fenpropathrin> Cypermethrin> Deltamethrin. Theorder of degradation rate registered as Cypermethrin> Deltamethrin> Fenpropathrin.4. The degradation of three pesticides was First-order kinetic model, and its half-life was11.0d to13.7d. Under the level of pyrethroid concentration designed in experiment, thecontents(<0.02/kg) of residues of Cypermethrin and Deltamethrin were far lower than themaximum residue limit defined in China and European Union and other countries. 5. The reasonable period to stop spraying pesticides before harvest was proposed. Theperiod was50day before to ensure apple safety.

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CLC: > Industrial Technology > Light industry,handicrafts > Food Industry > Fruits, vegetables,nuts processing industry > Standards and inspection of fruit and vegetable processed products
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