Study On UPLC-MS/MS Analysis Method Of 24 Pesticide Residues In Tea

In recent years,owing to the abuse of pesticide,increasing usage and government supervision is not enough,the problem of pesticide residues in agricultural products has become more and more prominent.Pesticide residues have become one of the main factors influencing the plant-derived food safety.Along with the progress of the society and people to enhance safety consciousness,plant-derived pesticide residues in food got more and more attention of governments around the world and the public.Meanwhile,some developed countries such as Japan and international organizations,the European Union established a series of strict green technical standard to limit our tea and other agricultural products export trade in exports of agricultural products in China.Pesticide residues as a technology barriers seriously affect China's tea,fruits and vegetables such as traditional export trade of agricultural products has become a great hidden trouble and hinder our country agricultural product export.At present,the analysis of pesticide residues level is not high,detection technology lags behind and quantitative analysis methods of pesticide residues in tea have been reported need spread pretreatment trial,need to use more poisonous reagent,and time consuming.The biggest challenge in the analysis of pesticide residues in tea is the interference of polyphenols and pigments.Pesticide residues in tea were with a degree of polarity or medium polarity,which dissolve out more easily in the infusing process,and high toxicity to the hidden trouble of the health of consumers.Aiming at the above problems,this paper selected the PVPP,PSA,and GCB as adsorbent materials,and a novel and rapid multi-residue analytical method has been developed and validated for the simultaneous determination of 24 representative pesticides?selected from organophosphorus,carbamates,heterocyclics?in agricultural samples?tea,apple,broccoli,and shallot?by ultra-performance liquid chromatography-electrospray tandem mass spectrometry?UPLC-MS/MS?following dispersive solid phase extraction.The method established is simple,rapid,and sensitive.The research results provide important theoretical and practical significance for the development and optimization of pesticide residue analysis methods in tea and fruit&vegetable,the elimination of matrix effects in complex samples and the safety regulation of pesticide residues in agricultural products.The main results were as fo1lowing:1.Study on purification of polyphenols and other interference matrix in tea.Calcium chloride?CaCl₂?,the graphene oxide?GO?and polyvinylpyrrolidone?PVPP?and several kinds of sorbent material were studied to eliminate the interference of matrix in the extract of tea,and the feasibility of adsorption materials applied in the detection of pesticide residue were studied.This paper was based on the content and polyphenol adsorption material removal amount,the change of the dry weight of the substrate,the calcium chloride,GO and PVPP best usage of optimization.The research results showed that the tea extract contains a large number of polarity strong interference material such as polyphenols.With the CaCl₂,PVPP dosage increased,the amount of polyphenols continue to decrease,that is to say the two adsorption material have better removal effect of polyphenols.At the same time,compared with the dry weight matrix,We found that the calcium chloride not only can effectively remove polyphenols,but also can play effective removal efficiency on some other unknown distractors.However,the optimum adding amount of pesticide used to add recycling application study found that after purification by calcium chloride in the samples,the recovery rate of methamidophos,acephate,omethoate and dinotefuran is relatively low,which can not meet the requirements of the detection method.Because of graphene oxide exists in the form of atomic layer structure,make the extract of graphene oxide processing in a film,easy to plug the filter head,filtrate out hard,is not conducive to analysis.The PVPP purified sample does not have these drawbacks,recoveries of adding all pesticides can meet the test requirements,so as much as possible in order to remove the tea matrix components,test finally choose PVPP as a new type of dispersive solid-phase extraction material applied to many kinds of pesticide residue detection.2.Multiple classes of pesticide residues for organophosphorus,carbamates,heterocyclics insecticides in tea,apple,broccoli,and shallot by UPLC-MS/MS was investigated.A multi-residue analytical method based on dispersive solid-phase extraction?d-SPE?coupled with ultra-performance liquid chromatography-tandem mass spectrometry?UPLC-MS/MS?was established for the simultaneous determination of 24 representative pesticides?selected from organophosphorus,carbamates,heterocyclics?in agricultural samples?tea,apple,broccoli,and shallot?.The agricultural samples were treated with vortex mixer in acetonitrile.Subsequently,the extract was cleaned up by d-SPE using a mixture of polyvinylpolypyrrolidone?PVPP?,primary secondary amine?PSA?and graphitized carbon black?GCB?as sorbents to absorb interferences prior to UPLC-MS/MS analysis.Total running time is no more than 10 minutes.Significant experimentalparameters,such as the type of mobile phase buffer,soaking time,extraction approaches,dispersive sorbent materials,and the amount of adsorbent,etc.were thoroughly studied and optimized.It was demonstrated that economical PVPP can be served as efficient dispersive solid-phase extraction materials for the elimination of polyphenols in tea,apple,broccoli,and shallot.Under the optimal experimental conditions,satisfactory linearity existed in the range of 0.001-0.2 mg·L^-1 for all the analytes with the correlation coefficients?r2?above 0.9935.Limits of quantification?LOQs?were 0.005 mg·kg-1for apple,broccoli,shallot sample and 0.01 mg kg-1 for tea sample.The recoveries varied from 72% to 113%with a relative standard deviation of less than 12%.The proposed method could be routinely applied for the analysis of pesticide residues in agricultural samples.