Detection Of Multiple Pesticide Residues In Complex Matrices By Dispersive Solid-phase Extraction-UPLC-MS/MS Based On Modified New-type Mesoporous Material

With the economic development and improvement of living standards and changes in people’s diet concepts,the demand and quality requirements of vegetables and tea for Chinese residents have gradually increased.The long-term unreasonable use of pesticides has increased the risk of agricultural product residue exceeding standards,which not only poses a serious threat to human health,but also severely hinders the development of China’s foreign trade.At present,there are still significant challenges in the detection of pesticide residues in typical crops such as chives,tomato,carrot,tea,wheat and peanut.Commonly used conventional purification materials such as PSA and C₁₈have disadvantages such as poor purification effect,low recovery rate,serious matrix interference,poor sensitivity,and difficulty in ensuring the accuracy of quantitative data.In recent years,the standards for pesticide residue limits at home and abroad have been increasing year by year,and the requirements for detection technology have become higher and higher.Therefore,the development of new purification materials to replace traditional materials is an important technical guarantee for the detection of pesticide residues in complex matrices.In this study,a new mesoporous material SBA-15 was synthesized and modified by octadecyl to obtain SBA-15-C₁₈,and its purification effect was further verified.The main results are as follows:1.SBA-15 was synthesized and modified by octadecyl to prepare SBA-15-C₁₈,which was characterized by FT-IRr and SEM.The results showed that SBA-15 and SBA-15-C₁₈ were successfully prepared,both of which have two-dimensional hexagonal through-hole structures,with similar shapes and similar sizes.The structure of SBA-15-C₁₈ obtained at the same time can maintain the complete structure skeleton even after octadecyl functionalization.2.The typical substrates of carrot,chives,tea,wheat,tomato and peanut were selected,and the conventional and new purification materials were optimized and evaluated.The results show that SBA-15-C₁₈ still has a balanced purification effect on 6 typical substrates when the amount of C₁₈ is reduced by 12.5%～50%.Based on the structural characteristics of SBA-15,SBA-15-C₁₈ also has the characteristics of C₁₈ adsorption of non-polar and weakly polar compounds.Therefore,SBA-15-C₁₈ can be used as a commercial C₁₈ substitute adsorbent,which has potential application value.3.Based on SBA-15-C₁₈,the analytical method of UPLC-MS/MS for detecting 32 pesticide residues in carrot,chives,tea,wheat,tomato and peanut was explored.The results showed that the average recoveries of the target pesticides in the six typical matrices ranged from 71.6%to 110.5%,and the relative standard deviations were between 0.66%and 9.64%.The target pesticide has a good linear relationship in the linear range of 0.0025（or 0.005）～0.5 mg/L,R²>0.996;the LOQ values of all target pesticides were 0.01 mg/kg.The method has the advantages of simple operation,high sensitivity,good purification effect,good stability and strong versatility.4.Collect 630 samples from large supermarkets and farmer’s markets in Tai’an City,Shandong Province,and apply the established analytical methods to detect pesticide residues in 6 typical agricultural products.The results showed that the detection rate of pesticides in all samples was 4.92%,the pass rate of the samples was over 99%,and the food safety risk was low.Through the optimization of conventional purification materials and new purification materials,it was preliminary determined that SBA-15-C₁₈ can be used as an alternative purification material for commercial C₁₈,and has potential application value.Based on SBA-15-C₁₈,an analytical method was developed for the detection of 32 pesticide residues in 6typical matrices by UPLC-MS/MS,and methodological investigations were conducted to meet the requirements for residue detection.The established analytical method is applied to actual sample monitoring,and the results show that the qualified rate of the product is over99%,and the food safety risk is low.