Detection Of Pesticide Residues In Fruits And Vegetables Based On Chromatography-Tandem Mass Spectrometry

Pesticide residue analysis is a technique for the analysis of trace compounds in complex matrices,which requires high sensitivity and specificity.The interference of matrix effect is a key problem in pretreatment.At present,QuEChERS method has been widely used as a simple,fast,safe and inexpensive analytical method.Although this method is fast and convenient,it is not effective for complex matrix purification.In this study,MWCNTs,z-Sep combined with QuEChERS pretreatment technology were used to extract and analyze pesticide residues in fruit and vegetable matrices by GC-MS/MS and LC-MS/MS.we established a new method for the determination of multiple pesticides in vegetables and fruits.The results are as follows:1.We choose mixed vegetables as sample.We modified traditional QuEChERS method by adding MWCNTs and z-Sep in the purification steps.182 representative pesticides were selected to optimize the purification conditions.Finally,the mixed purification system of PSA,MWCNTs and Z-Sep was used.The dosage of MWCNTs(TNM3)was 30 mg,the dosage of Z-Sep was 80 mg,and the dosage of PSA was 125 mg.Samples after purified were almost colorless.2.We studied the difference between the new purification system(PSA combined with MWCNTs and Z-Sep)and the traditional QuEChERS purification system(PSA combined with GCB and C18).Through the sample photos,the pigment content of adding MWCNTs samples was less than adding GCB samples.Meanwhile,through the chromatogram,the number of impurity peak was obviously reduced by adding MWCNTs.At the same time,compared with the traditional QuEChERS method,adding z-Sep greatly reduces the matrix effect and shows obvious superiority in the purification effect.3.We established gas chromatography tandem mass spectrometric and and liquid chromatography tandem mass spectrometric methods for 182 kinds of pesticides in vegetables and fruits.GC-MS/MS uses 3-ethoxy-1,2-propanediol,L-(+)-Gulosic acidγ-lactone and D-sorbitol as analytical protectors.The three analytical protectors can provide co-efflux protection or counteract the matrix effect for compounds of RT 5-9min,7-17min,and 7-34min;LC-MS/MS used chromatographic column ACQUITY UPLC HSS T3(100 mm x 2.1 mm,1.7 um)to analyze 123 pesticides,dilution volumetric method(dilution 1 times)reduced the matrix effect of the analysis items.The analysis was performed in multi reaction monitoring (MRM)mode.Under the MRM mode,182 kinds of pesticides can be separated.The linear correlation coefficients(r~2)are higher than 0.99 in the range from10 to 200μg/kg.4.Recoveries were evaluated in four representative matrices(spinach,ginger,eggplant,a pple)with the spiked concentrations of 10μg/kg,20μg/kgand 50μg/kg in all cases(n=6).T he results showed that the recovery of 182 pesticides ranged between 56.0%and 124.0%,and the relative standard deviation was less than 22.0%.Based on the results presented above,the modified methodology meets the requirements for multiple pesticide determination in fruits a nd vegetables and will have broad applications in food analysis.