Determination Of Pesticide Residues In Fruits And Vegetables Using Liquid Chromatography-tandem Mass Spectrometry

Pesticides residue analysis has become an important component of global food safety and environmental monitoring.Many countries and international organizations have established strict standards and set the maximum residue limits(MRLs)for pesticides in agricultural products,guaranteeing food safety and ensuring import and export trade.Many analytical methods and technologies have been reported for pesticides residues analysis.Liquid chromatography-tandem mass spectrometry(LC-MS/MS)has become a powerful technique for pesticide residue analysis due to its high specificity and sensitivity.Based on the analysis above,the determination of strong polar pesticides and pesticide multiresidues in fruits and vegetables were established using liquid chromatography-tandem mass spectrometry.The main researches are presented as following:The first chapter is to overview the sample preparations and detection technologies of pesticide residues.The solid phase extraction(SPE)and QuEChERS are introduced in detail as well as liquid chromatography-mass spectrometry(LC-MS),including the liquid chromatography separation and the application of low resolution tandem mass spectrometry and the high resolution mass spectrometry.A liquid chromatography-tandem mass spectrometry(LC-MS/MS)method for simultaneous determination of two hydrophilic aminoglycosides,kasugamycin and validamycin-A,in a variety of matrices(apple,cabbage,cucumber,lettuce,tomato,and eggplant)has been developed.In the proposed method,acetonitrile and water containing 0.1%formic acid were used as mobile phases without any ion pairs or buffer additives.The ReproSil 100 C1g column was successfully used for strong polar compounds analysis with well-shaped peaks and good ion intensities.The methanol/water(70:30,v/v)with pH adjusted to 5.5 provided best recoveries was selected as the extraction solvent.The combination of HLB and SCX cartridges minimized signal suppression/enhancement which led to matrix effects in the range of-12.6 to 6.11%only and permitted satisfactory recoveries within the range of 81.7-108%.The relative standard deviations(RSDs)are below 13%.The method validation was based on the European SANTE 11945/2015 guidelines.Therefore the proposed method is an efficient approach for kasugamycin and validamycin-A analysis in complex fruits and vegetables at low residue levels.The third chapter introduced a multiclass pesticides analysis in vegetables.A multiresidue method based on a modified QuEChERS extraction procedure,followed by ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS)was developed and validated for the determination of 16 pesticides in wild cabbage,pimento,tomato and lettuce.Using the ultra pe:rformance liquid chromatography(UPLC),a mixture of 16 pesticides was eluted within 10 min.The samples were extracted with 0.2%formic acid in acetonitrile(0.2:99.8,v/v)and the extract solvent is diluted 1:1 with a mixture of methanol/water(50:50,v/v)to enable quantitation by UPLC-MS/MS.The recovery studies were carried out at 4,20 and 40?g/kg levels for the target compounds with extraction performed in five times.Average recoveries ranged from 72.2-119%with the relative standard deviations(RSDs)lower than 17%.The method presented is suitable for routine pesticide multiresidue analysis in vegetables.