Determination Of Multi Pesticide Residues In Fresh Tea Leaves And Study On The Law Of Three Pesticide Residues

In this paper,the samples were pretreated by Qu ECh ERS method after optimization of three different cleanup agents,and the multi pesticide residue detection method in tea fresh leaves was carried out by liquid chromatography tandem triple quadrupole mass spectrometry（UHPLC-MS/MS）,then the field digestion dynamic rules of three pesticides including indoxacarb,acetamiprid and buprofezin were analyzed and summarized,which may provide a scientific basis for the pesticide detection and its production of tea.A method for the determination of 80 pesticides and metabolite residues in fresh tea leaves by UHPLC-MS/MS was established.In the experiment,through the optimization of mass spectrometry conditions,a multi reaction monitoring method for 80 pesticides was established,and different conditions such as different extraction solvents,extraction time and extraction methods were explored.The optimal combined dosage of purification agents PSA,C₁₈ and multi wall carbon nanotubes was optimized by orthogonal experimental design.After the method was established,the matrix effects of 80 pesticides and metabolites were investigated.Through methodological evaluation,the method has good accuracy and precision.The method is simple,rapid and environment-friendly,which is conducive to a rapid and comprehensive understanding of pesticide residues in fresh tea leaves.The recovery of pesticide residues was determined by blank sample addition method.Fresh tea leaf samples were extracted with acetonitrile,purified after salting out,detected by ultra high performance liquid chromatography tandem triple four pole mass spectrometer,and quantified by external standard method.The addition level of 80 pesticides in fresh tea leaves was 5μg/kg～50μg/kg,the average recovery was 68.4%～119.7%,and RSDs was1.9%～13.0%.In this method,the linear range of 80 pesticides is 0.002μg/m L～0.50μg/m L,the correlation coefficient is 0.996,and the LOD of the method is 0.89μg/kg～8.95μg/kg,LOQ 2.97μg/kg～29.83μg/kg.The above data show that the accuracy,precision and sensitivity of the method meet the requirements of pesticide residue detection.At the same time,this paper studied the dynamic digestion law of indoxacarb,acetamiprid and buprofezin.The field digestion dynamic test showed that the digestion dynamic test of three pesticides with different dosage accorded with the first-order kinetic equation.Through the research on the dynamic digestion law of pesticides,the theoretical results have important guiding significance for determining the safe interval of pesticide use,reducing pesticide residues in tea,improving tea quality and improving tea export quality.