The Research On The Quality Control System Of 121 Pesticide Residues In Fruits And Vegetables

Fruits and vegetables in the process of growth and storage in order to prevent diseases and insect pests, pesticides always be sprayed on in a certain amount, for the most part was erosion due to the sun, the rain, but trace pesticide still residual in the product. Due to pesticide residue problem, fruits and vegetables in the import and export trade in our country frequently suffer from the limitation of technical barriers. So it has very important practical significance to establish a rapid screening detection method of pesticide residues.This paper divided 121 kinds of pesticides into four groups, according to the retention time in GC-MS. And prepared mixed standard solution according to different response value with four groups pesticides, and established monitoring method of selected ion for each groups. Sample analysis was performed by GC-MS and SIM mode. Pesticides were positively confirmed by retention times and ratios of characteristic ion’s abundance, quantified by method of ESTD. In the sample pre-treatment, pesticide residues were extracted using acetonitrile.Then sample extract was cleaned up adopting solid-phase extraction. Sample extract was passed through Carbon Aminopropyl Sep Paks. The calibration equations was established by matrix-matched calibration standards. The linear relation of all pesticides was satisfactory and the correlation coefficient was higher than 0.996. The recoveries of pesticides were in the range of 60.57%～117.64%, but the recoveries of Prochloraz, Diflufenican, Tolylfluanide, Propham, Dichlorvos were in the range of 60%-70%, the recoveries of other pesticides were in the range of 70%-120%. And the relative standard deviations (RSDs) were less than 15%. MDLs were in the range of 0.003-0.375mg/kg, the MDLs of 42 pesticides were lower than GB/T19648-2006. Programmed-temperature was used in this analysis method and the analysis time needed 38min. A total sampled 4 times, and can complete detection of 121 pesticides. Above results fit for the standard of domestic and foreign export pesticide detection analysis in vegetables and other agricultural products.The paper used cucumber as matrix, and compared total iron chromatogram (TIC) of standard pesticides between the standards dissolved in normal organic solvents and matrix-matched standards. It was demonstrated that response value of matrix-matched standards higher than normal organic solvents standards or be the same. For pentafluorobenzene, chloroneb, hexachlorbenzene, alpha-HCH, quintozene, y-HCH, Isoprothiolane, dimethoate, runnel, vinclozolin, Chlorpyrifos, delta-HCH, heptachlor-epoxide, a-endosulfan, p,p’-DDE and pebulate, the matrix effect could be ignored. But other pesticides show matrix enhancement effect.The paper extracted matrix of cucumber, cabbage, apple and compared the matrix effect of C group pesticides in 3 matrix. It was demonstrated that the matrix effect also depends on the chemical nature of the analyte. The matrix effect of some pesticides have obvious variation in 3 matrix. So, the matrix effect couldn’t be ignored. And this paper showed that matrix-matched standards must be used as calibration mode to compensate for the matrix effect.