The Residue And Degradation Of Main Pesticides In Tobacco Leaves And Soil

Acetamiprid,25% flumetralin EC and 25% rimsulfuron WG was studied in the experiment.According to the require of ?pesticide residue test standard?,field experiment of pesticide residue was designed in Shanxi to study the residue detection analysis,degradation dynamic and final residue of different types of pesticides.The experiments of prevention and cure of acetamiprid,flumetralin and rimsulfuron were designed in order to provide data support for the rational and safe use of pesticides and the setting of the limitation of pesticide residue.The results as follows:1.According to the recommended dosage of pesticide registration to spray,the decrease order of the efficient of prevention and cure was 5% acetamiprid EC,3% acetamiprid ME,70% acetamiprid WDG and 40% acetamiprid WDG.After 10 d of spraying,the efficient of acetamiprid EC and acetamiprid ME reached 98.22% and 94.37% respectively.After 20 d of spraying flumetralin,the increase order of fresh weight of axillary bud was diluted 100 times,diluted 300 times,diluted 200 times,diluted 450 times,CK.The leaves area and the effect of the treatment of flumetralin in the treatment of diluted 300 times was relatively large.the dosage of rimsulfuron at 150 g/hm2 had the best effect on tobacco growth and the control of weeds.2.The residues of acetamiprid,rimsulfuron and flumetralin in tobacco leaves and soil were determined by the method of acidic acetonitrile extraction,matrix solid phase extraction purification,UPLC-MS / MS and GC ECD.The results showed that: the detection limit of acetamiprid,rimsulfuron and flumetralin was 0.01mg/kg.The average recovery rate of acetamiprid ranged from 88.4% to 96.9%,the RSD ranged from 3.86% to 6.74%;The average recovery rate of flumetralin ranged from 86.49% to 97.93%,the RSD ranged from 1.77% to 6.38%;he average recovery rate of rimsulfuron ranged from 80.40% to 96.70%,the RSD ranged from 1.88% to 7.28%.The detection limit and recovery rate both met the requirement of tobacco residue analysis,and the method was rapid and accurate.3.The degradation dynamics of different types of pesticides were determined.The half –time in tobacco leaves of 5% acetamiprid EC,3% acetamiprid ME,40% acetamiprid WDG and 70% acetamiprid WDG was 1.92~2.88 d,3.26~5.52 d,3.26~5.24 d and 4.61~6.27 d,respectively.The half-time in soil was 1.54~5.44 d,4.71~6.62 d,1.84~4.47 d and 5.72~7.70 d.The original sediment of acetamiprid under pot condition was higher than the field,but the degradation rate was slower than the field.The absorption peak value of flumetralin in tobacco leaves was 24.44~31.22 mg/kg,and the half-time in tobacco leaves was 6.33~6.79 d.The original sediment of flumetralin was 1.38~2.32 mg/kg,the half-time in soil was 6.33~6.79 d,and the degradation at 21 d reached 90%.The original sediment of rimsulfuron was 0.225~0.322 mg/kg,the half-time in soil was 8.15~9.24 d,and the degradation at 21 d reached 80%.Acetamiprid,flumetralin and rimsulfuron are easily degradable pesticides.4.The final residues of different dosages,spraying times and sampling interval were determined.After the last spraying of 14 d,the maximum residues in tobacco leaves of 5% acetamiprid EC,3% acetamiprid ME,40% acetamiprid WDG and 70% acetamiprid WDG were 0.52 mg/kg,0.57 mg/kg,0.54 mg/kg and 0.74 mg/kg,respectively,and the maximum residues in soil were 0.027 mg/kg,0.020 mg/kg,0.026 mg/kg and 0.07 mg/kg.The difference of different pesticide formulation in tobacco leaves and soil was not significant,and they were all far below the guidance of tobacco limited to 2.5 mg/kg.After spraying 14 d,the largest final residue of flumetralin in tobacco leaves was 0.189 mg/ kg,the largest final residue in soil ranged was 0.198 mg/kg,and they were both far below the maximum residue limit of flumetralin in tobacco leaves ruled by GRLs 5 mg/kg.After 21 d,the maximum final residue of rimsulfuron was 0.019 mg/kg;the maximum final residue in soil was 0.028 mg/kg.Just follow the recommended dosage and use frequency to spray,try to extend tobacco harvest interval after the application,tobacco pesticide residues can be degraded to the guidance and residue limit(GRLs)set by the international tobacco Cooperation Center(CORESTA).