| Vegetables are the second largest crop in my country’s planting industry.They have high yields and short growth cycles,but they are extremely vulnerable to pests and diseases.Pesticides,as a powerful means to prevent and control vegetable pests and increase vegetable yield,are widely used in vegetable production and planting.The extensive use of pesticides has led to the gradual accumulation of pesticide residues in fruits and vegetables.This phenomenon is particularly serious in vegetable planting(due to the short maturity period of vegetables and short spraying intervals,pesticides cannot be completely metabolized),resulting in more and more Safety hazards.Therefore,it is very important to establish a pesticide residue detection method with high throughput,high sensitivity,simple operation,fast and accurate.At present,gas chromatography-tandem mass spectrometry(GC-MS/MS)technology has obvious advantages in high-throughput detection.It has high sensitivity and strong specificity;QuEChERS is one of the fastest growing methods in pre-processing technology,and it has fewer extraction steps,The operation is simple and safe,economical and environmentally friendly.Therefore,this experiment is based on QuEChERS combined with GC-MS/MS technology to optimize and verify the pretreatment methods for various pesticide residues in fruits and vegetables,and establish an efficient and rapid determination method for 93 pesticide residues in fruits and vegetables.The main research contents and conclusions are as follows:1.Using QuEChERS technology combined with GC-MS/MS to determine 93 pesticide residues in fruits and vegetables,and optimize the parameters of the method.The results showed that 10 mL 0.5%acetic acid-acetonitrile solution was used as the extraction solvent,ultrasonic extraction Ultrasonic 30min,2 g anhydrous sodium sulfate and 2.5 g sodium chloride were used as dehydrating agents,700 mg anhydrous magnesium sulfate,150 mg N-propyl After purifying and concentrating ethylenediamine(PSA)and 30 mg graphitized carbon black(GCB)as purifiers,GC-MS/MS was used to quickly detect 93 kinds of pesticide residues.The determination effect was good and the pesticide recovery rate was high.The matrix-matching standard solution method was used to evaluate the matrix effect of 93 pesticides in the four matrices.The results showed that the method has good purification effect and can effectively reduce the influence of matrix effect.2.Methodological verification of of the established method showed that 93 pesticides showed a good linear relationship in the range of 0.010～0.200 μg/mL,the correlation coefficient r was all greater than 0.9900,and the detection limit(LOD)of the method was 0.01～5.08 μg/kg,the limit of quantification(LOQ)is 0.05～16.92 μg/kg.At the three spiked levels of 0.01 mg/kg,0.05 mg/kg,and 0.10 mg/kg,the average recovery and relative standard deviation(RSD)of each component in the four matrices of radish,cucumber,spinach,and strawberry are:Radish 69.0%～115.6%,RSD0.76%～12.39%,Cucumber 69.0%～121.3%,RSD0.51%～12.36%,Spinach 70.5%～121.0%,RSD0.34%～12.24%,Strawberry 70.0%～126.3%,RSD 0.17%～11.49%.Comparison and analysis with the national standard general method showed that the method is simple,fast,sensitive,and practical,with better method performance indicators,and can meet the requirements for high-throughput detection of pesticide residues in fruits and vegetables.3.The established method was used to test 213 actual samples.The results showed that the overall detection rate of pesticides was 31.9%,and the unqualified rate was 2.3%.Procymidone,fenoxyfen,acetamiprid,etc.were tested in vegetables The exit rate is higher.The detection of large quantities of fruits and vegetables proves that the method has simple operation steps,qualitative and quantitative accuracy,and can be used for the analysis of pesticide residues in various fruits and vegetables. |
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