Study On The Residue And Degradation Of Lambda-cyhalothrin On Pakchoi And Cabbage

Lambda-cyhalothrin is a new pyrethroid insecticide,which has strong touch and stomach toxicity to pests and is suitable for the prevention and control of many pests on vegetables,cotton,fruit trees,tea trees,and tobacco and other crops.In recent years,with the ban of highly toxic pesticides,lambda-cyhalothrin has become one of the most widely used pesticides in China.Due to the high multiple cropping index of vegetables and the frequent occurrence of pests and diseases,it is often used in large quantities in vegetable production apply to pest control..However,the utilization rate of chemical pesticides is currently only about 38%.The use efficiency of pesticides and pesticides flash in crops.Deposition,degradation,disappearance rate and other factors.The main conclusions obtained were listed as follows:1.A method for the simultaneous determination of lambda-cyhalothrin residues on cabbage and pakchoi was established by high performance liquid chromatography and tandem mass spectrometry.Gas chromatography method was used to detect the average recovery of lambda-cyhalothrin on pakchoi and cabbage from 0.02 to 2.0 mg/kg was 86.60%to 106.51%,and the relative standard deviation was 1.97%to 8.81%.This method optimizes the method of sample extraction and purification,which is more convenient and reduces the use of organic reagents.The range of added quality scores was significantly improved.The method is simple,rapid and can meet the requirements of pesticide residue analysis.2.Studying the effects of different spraying amounts on the initial deposition of lambda-cyhalothrin on pakchoi and cabbage,it was found that there were significant differences in the amount of pesticide deposition on Chinese cabbage and cabbage.At a certain dosage,increasing the amount of pesticide spraying could not increase the amount of pesticide deposition on leaves.3.Studying the effects of cyfluthrin on the initial deposition and half-life of Chinese cabbage and cabbage at three application doses.The results showed that the deposition amount of the same species of leafy vegetables was significantly different under different dosage.The half-life of different cruciferous vegetables was also significantly different,the half-life of pakchoi was 1.68-1.87 days,and that of cabbage was 2.45-3.10 days.4.Through experiments on pakchoi and cabbage during different growth periods,it was found that the initial deposition of pesticides on cabbages and cabbages in different growth stages was significantly different,the amount of pesticide deposited on cabbage at bolting stage>maturity stage,and the amount of pesticide deposited on cabbage at different growth stages was significantly different,the Cabbage knotting stage>rosette stage.5.The major metabolites of lambda-cyhalothrin on pakchoi and cabbage were determined by gas chromatography-mass spectrometry and liquid chromatography.It can be presume that the degradation of lambda-cyhalothrin on cabbage and pakchoi is 3-phenoxybenzaldehyde.