| As the development of science and technology, the kinds and number of chemical pesticides are increasing day by day. With the increasing and using excessively in agricultural application, concerns have been raised by the public regarding its residue problems and the hazard of poisoning. Development of quick, easy and effective multi-pesticide residues determination method is needed hardly, in order to reinforce the management of pesticide abuse. Sample pretreatment is the critical section in residue determination,it's the key indicator to measure the advancement and practicability of a new determination method. Nowadays, the technological distance between our country and developed countries is not the instruments but the sample pretreatment such as extraction and clean steps. In 2003, Anastassiades and Lehotay, et al. from the eastern regional research center of United States agricultural department developed a fast and easy multi-residue method employing acetonitrile extraction /partition- ing and"Dispersive solid-phase extraction"for the determination of pesticide residues in produce. The method, compared to other methods has the advantage of quick, easy, cheap, effective, rugged, and safe known as QuEChERS method. Later on, this QuEChERS method was collaboratively studied among 13 labs in 7 countries, and became AOAC Official Method 2007.01 in 2007. Accordingly, study on the critical steps in QuEChERS method and improve it, made it fit for our needs in multi-pesticides residue have important means. The main object in our study is to discuss the critical factor impact the results, choose the most popular used pesticides in our county and the pesticides on the routine monitoring list of ago-products quality as our research targets and develop an adaptive method based on the QuEChERS method for the determination of multi-pesticides residue in vegetables and fruits, details are as follows:(1) Comparing was conducted between extract solvents, amount of salt and dispersive sorbent used in pretreatment and its effect on cleanup. Results as follows: the ratio between fresh sample amount and extract solvents is 1:1, the sample amount: anhydrous magnesium sulfate: sodium acetate is 10:4:1. Adding of toluene at ration of 1:3 to extraction liqulid can effectively improve the planner pesticides recovery decreases caused by the GCB absorb.(2) Develop a GC-MS/MS method based on the QuEChERS procedure to determinate 40 kinds of pesticide residues in vegetables; the linearity, precision and accuracy were investigated. The mean recoveries of all pesticides were in range from 85% to 120%, relative standard deviation were from 3.1% to 18.3% at the 0.05 mg/kg,0.1 mg/kg and 0.2mg/kg Spike level,the precision and accuracy of this method meet the requirement of residue analysis. The limit of determination of 40 kinds of pesticides is between 0.002μg/kg~2.12μg/kg, limit of quantity is between 0.007μg/kg~7.092μg/kg, which is much lower than the most reported GC or GC-MS determinate methods.(3) Develop a LC-MS/MS method based on the QuEChERS procedure to determinate 29 kinds of pesticide residues in vegetables. The liquid chromatography conditions and mass spectrometry conditions were optimized; linearity, precision and accuracy of the method were investigated. The method is reliable and stable that the recoveries of almost all pesticides were in the range from 70% to 119% at the 1μg/kg, 5μg/kg and 10μg/kg spiked level, and the RSD were all below 15.5%. The limit of determination of 29 kinds of pesticides were in the range from 0.005μg/kg to 0.352μg/kg, limit of quantity were in the range from 0.015μg/kg to 1.176μg/kg.(4) The QuEChERS method was applied to more matrixes such as tomato, spinach, cabbage, pear and apple, the applicability and usage scope was discussed.
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