Study On Determination Of Multi-residue Pesticides In Concentrated Fruit And Vegetable Juices Using Liquid Chromatography Tandem Mass Spectrometry(LC-MS/MS)

Nowadays people pay more attention to the harms that pesticide residues make on human health and the environment. Therefore, many different countries have promulgated their own residue limits in the international trade. Various pesticides are applied to fruits and vegetables, may be transferred to fruit and vegetable juices contributing to multi-residue in the juice, which may be do hazards to human health. Many countries increased the detection items that the import and export of the fruit and vegetable juice should be detected, making more serious standards and lower MRL, so juices export of our country are facing more and more technical barriers. In the last years trends in sample treatment are towards the miniaturization and simplification of the methodologies to overcome the disadvantages caused by using high amounts of toxic solvents, due to these advantages the QuEChERS method has had worldwide acceptance. This paper particularly introduced the progress in the QuEChERS method technology and the method principle. This paper studied extraction, purification and LC-MS/MS detection conditions of pesticide residues in concentrated fruit and vegetable juices and developed a new sample treatment, extracting by acetonitrile (containing 1% acetate acid),cleaning-up by Waters Sep-Pak Vac SPE. This paper determine the high-performance liquid chromatography-tandem mass spectrometry conditions by experiment,using the retention time and ion-pair compound to do quanlitative analysis, the external standard to quantify, then establishing the method for determination of 248 pesticides in concentrated fruit and vegetable juices, including organophosphate, organochlorine and pyrethroid category. The main results were as follows:1 In this research, we optimized the extract solvent, extract method, clean up method, then established a preparation method that extracted by acetonitrile (containing 1% acetate acid),cleaned-up by Waters Sep-Pak Vac. the overall recoveries were in the range of 70% ~120% and the relative standard deviations were all below 20%.2 In this research, we optimized the MS/MS condition, chose the suitable liquid chromatography column, mobile phase programe and flow rate, the reconstitute solvent, then established LC-MS/MS detection method for 248 pesticides. 236 pesticides correlation coefficient above 0.99, accounting for 95 percent of the detected pesticides. The limits of detection were 0.01~56.77μg/kg and the number of the pesticides that the limits of the quantification below 10ppb is 206, accounting for 83 percent of the detected pesticides. So we think the method can be used to quantify the pesticides in the juices.This method is simple, rapid and need short time, and its sensitivity and accuracy meet the requirements of the multiple pestiside residues. This method is applicable to confirm 248 pesticide residues in concentrated fruit and vegetable juices.