Application Of The QuEChERS Method In Multi-Pesticide And Multi-Veterinary Residues In Food

Food safety is one of the primary issue, which the people and government pay close attention to. Pesticide residues and veterinary drug residues are common chemical contaminants. It is significant to develop a simple, fast and efficient method for the analysis of pesticide and veterinary drug residues. This paper develops two determination methods: the determination of pesticides in the vegetables and the determination of veterinary drug residues in fish. Furthermore, the matric effects of different kinds of pesticide and veterinary drugs in different matric were evaluated.And the paper makes assessment on the uncertainty of mixed standard solution during the preparation.The main content of this thesis is as follows:1.A method was developed for the simultaneous determination of 136 kinds of pesticide residues in vegetables by high performance liquid chromatography-tandem mass spectrometry method. Also the matric effects of different kinds of pesticide in different matric were evaluated. Based on QuEChERS, the analytes were extracted with 1% acetic acid in acetonitrile, and then purified by PSA, C18 and anhydrous magnesium sulfate. The analytes were separated on a CAPCELL PAK C18 column,detected by MS performing in multiple reaction monitoring(MRM) mode. In this study, the calibration curves of 136 pesticide residues were linear in the range of5.00 ~ 100 μg/L with correlation coefficients between 0.9951 ~ 0.9999. The recoveries of 86.13% analytes at three spiked concentration levels(20, 50, 200 μg/kg)ranged from 70% to 130%, with the relative standard deviation(RSD)between 0.2%and 13%. Matrix effects of most compounds are independent except for some polar compounds. The method is simple, rapid, efficient, insignificant matrix effects and suitable for the determination of multi-pesticide residues in vegetables.2.A method was developed for the simultaneous determination of sixteen kinds of sulfonamides, two kinds of amphenicols, malachite green and leucomalachite green in fish by high performance liquid chromatography-tandem mass spectrometry method. Matrix effects of different kinds of veterinary drug in different concentrationwere evaluated. Based on QuEChERS, the analytes were extracted with 0.1% formic acid in acetonitrile, and then purified by PSA, C18 and anhydrous magnesium sulfate.The analytes were separated on a Waters CORTECH UPLC C18 column, detected by MS performing in multiple reaction monitoring(MRM) mode. In this study, the calibration curves of 20 veterinary drug residues were linear in the range of 0.50~200 μg/L with correlation coefficients between 0.9938~0.9999. The recoveries of the analytes at three spiked concentration levels(20, 50, 100 μg/kg) ranged from 85%to 110%, with the relative standard deviation(RSD) between 2.1% and 11.6%.Matrix-matched standard solution is necessary in the analysis of low concentration.The method is applied and validated for the determination of multi-veterinary drug residues in general fish.3.In this section, the uncertainty factors of 27 pesticides mixed standard solution during the preparation were evaluated. The preparation uncertainty of mixed standard solution was calculated with the top-down calculation method. In the end, the expanded uncertainty was presented. The result indicated that the dilution of the standard solution is the most important factor during the preparation of the mixed standard solution. This method provides reference for the accurate determination of pesticide residues.