Study On The Residues Determination And The Residual Dynamics Of Acetamiprid In Tea And Soil

Acetamiprid is a neonicotinoid insecticide that is used for the control of sucking-type insects on leafy vegetables,fruiting vegetables,cole crops,citrus fruits,pome fruits,grapes,'cotton and ornamental plants and flowers.In tea,Acetamiprid show an excellent effect for the prevention of Empoasca pirisuga Matumura.To evaluate the metabolic behavior of the residues in tea cultivation environmental media and the stability of acetamiprid in tea,and provide a scientific basis for pesticide registration,the residues and the residual dynamics of acetamiprid in tea and soil,and the storage stability have been studied.The main findings are as follows:Residues analysis method of acetamiprid in tea and soil by GC-ECD for supervised residue trial analysis was studied.Fresh tea leaves were extracted with acetonitrile and water(V:V=4:1)by mechanical shaking and cleaned by liquid-liquid partition using petroleum ether and dichloromethane,while soil samples were extracted only by acetonitrile.Both tea and soil samples were purified by Florisil column chromatography and analyzed by GC equipped with an DB-608 capillary column.Detection limit of acetamiprid was 0.02ng.The limit of determination was 0.01mg/kg for tea and soil.The average recovery of acetamiprid from tea samples spiked at 0.01 to 1mg/kg levels were varied from 78.9 to 103.8%.Similarly,average recovery from soil samples fortified at 0.01 to 1 mg/kg varied from 81.8.to 91.4%.At the same time,the relation standard deviation was 1.37%?3.92%,2.58%?6.83%,respectively.The results indicated that the method was sensitive,reproducible and practical for the residue detection and analysis of acetamiprid in tea and soil.A HPLC-UV method for the detection of acetamiprid in tea was established.A high-performance liquid chromatograph,equipped with a reverse phase C18 column and UV detector was used.Acetamiprid was extracted by acetonitrile from tea samples and purified by PSA adsorbent.The average recovery of three spiked concentration levels for acetamiprid in tea were 88.2%,90.5%and 90.2%,respectively,with the relation standard deviation were 2.93%,2.59%and 4.59%,respectively.The established HPLC method was fast,simple,fitness for the residue analysis of storage stability of acetamiprid in tea.The residue degradation of acetamiprid in tea and soil using GC-ECD was investigated.The experiment results of two years in three place were that the degradation half-life of acetamiprid in tea and soil was between 3.36?16.1d and 1.23?16.5d,respectively,which showed that the degradation of acetamiprid in tea and soil were followed first-order kinetic equation,and its degradation was rapid and it belongs to the easy degradation pesticides.The final residues of acetamiprid in tea and soil were determined by GC-ECD method.The tea was sprayed twice and three times with high dose(135g a.i/ha)and low dose(90g a.i/ha)with a 7 day spraying interval.Tea and soil samples were taken after 5,7,10 d of the last spraying.The final residue in tea was between<0.01mg/kg?7.83mg/kg,and between<0.01 mg/kg?0.0652mg/kg in soil.According to the final residue experiment data,the pre-harvest interval of acetamiprid on tea was recommended of 7 day.The MRL of acetamiprid on tea was recommended of 5mg/kg based on risk assessment.The storage stability of acetamiprid in tea under different temperature conditions was investigated.The experimental result show that acetamiprid degraded easily under room temperature and been more stable under-20? in tea.In order to ensure the accuracy of the residual results,samples should be stored frozen at-20? condition during the course of the residual experiment.