Study On Rapid Screening Of Multipesticide Residues In Vegetables And Fruits

In our country safety of vegetables and fruits hidden great risks because of decentralized production mode and irrational use of pesticides. In recent years, in order to ensure the safety of consumption and the prevention of emergencies, the state had increased the intensity of monitoring of pesticide residues in vegetables and fruits, test items and the stricter requirements of the pesticide residues, which made the detection work more difficult. This paper focused on the sample pretreatment of QuEChERS and QuEChERS combined with DLLME respectively followed by GC-MS/MS or GC-TOF/MS technology, carried out the study of rapid screening of pesticide residues in vegetables and fruits, the main contents and results are as follows:In the first part, It described the current situation of analytic method of pesticide residues, the advantages and disadvantages of QuEChERS and related sample pretreatment technology. Then, It introduced the recent developments of DLLME detailedly and its application in food safety analysis at home and abroad.The second part, an analytical method for simultaneous determination of129pesticides in vegetables and fruits was established which based on optimized QuEChERS with GC-MS/MS. The sample were extracted with acetonitrile (containing1%acetic acid), then the extracts were determined by GC-MS/MS in multi-reaction monitoring (MRM) mode after being cleaned up with mixed solid-phase dispersion, and the external standard method was applied to quantify the pesticides. The results showed that all the129pesticides had good linearity in certain ranges with the correlation coefficients (r) higher than0.98. The average recoveries of the most of129pesticides in different matrices were in the range of66.2%～124.7%at the spiked level of10μg/kg, with relative standard deviations (RSDs) of0.9%～24.4%. The limits of quantification (LOQs) of the method were0.03μg/kg～16.7μg/kg. The results demonstrated that the developed method using tandem mass spectrometry overcame the interference factors in QuEChERS combined with mass spectrometry was simple, rapid, sensitive and high efficient for rapidly screening of multiple pesticide residues in vegetables and fruits.The third part, a simple and efficient method was firstly developed in and abroad using QuEChER and DLLME coupled with gas chromatography-time of GC-TOF/MS for rapidly screening of116pesticide residues simultaneously in vegetables and fruits. Parameters affecting purification and extraction efficiency in both QuEChER and DLLME procedures, such as the dosage of purificant, type and volume of extraction and dispersive solvents, volume and pH of water, salt effect were investigated and optimized to achieve the best extraction efficiency. Database of GC-TOF-MS for the screening of pesticides was also established. The results showed that in the optimum conditions, all the116pesticides had good linearity in a certain range and the correlation coefficient(r) was higher than0.98. The average recoveries of the most of the pesticides in different matrices were in the range of60%～120.0%at three spiked levels of10μg/kg,30μg/kg,50μg/kg with RSDs of3.2%～22.1%. The enrichment factor was20times, the limits of detection(LOD, S/N≥3) and LOQ (S/N≥10) of the method were respectively0.01μg/kg～20μg/kg and0.03μg/kg～66μg/kg. The proposed method had the advantages of being easy to operate, having high-enrichment factor, low cost and friendly environment, being sensitive and high efficient, using low consumption of organic solvent. It provided a new way for rapid screening of pesticide residues.Rapid screening of pesticide residues in vegetables and fruits was studied in this paper. Under no standard substances conditions in the method developed above, relevant information based on pesticide databases directly screened pesticides and the calibration curve quantified the pesticides screened out accurately. It realized the fast qualitative and accurate quantitative detection of the target analyte. The results of this study provided an useful screening information and efficient means of detection for the further research of the screening technology of multi-pesticide residues and the work of pesticide risk assessment, and a good practical value.