Research On Separation And Analysis Methods Of Pesticide Residues In Tea

As people pay more and more attention to food safety,the demand of food safety is more and more strict at home and abroad.The sensitivity of"pesticide residues"is also increasing,and pesticide residues in tea has always been concerned,which is one of the important factors affecting the development of tea industry.With the research of pesticide residues in tea,it is of great significance to establish an efficient and accurate method for the separation and analysis of pesticide residues.In order to establish a simple,rapid,cheap and efficient sample pretreatment method,this paper studies the separation and analysis of pesticide residues in tea.The results of the study are as follows:1.Establishment of simultaneous separation and analysis of 11 kinds of organochlorine and pyrethroid pesticide residues in tea.The MSPD method was applied to the pretreatment process of tea samples,the types and content of dispersants,the kinds and amount of the fillers,the types and dosage of eluent were optimized,and the feasibility of the method was verified,in the range of 0.1².0 mg/L,the linearity is good,the linear correlation coefficient is 0.9909⁰.9999.When the scalar volume was 0.1 mg/L,0.6 mg/L and 1.0 mg/L,in addition to?-666 recovery is relatively low,the recoveries of 11 kinds of organochlorine and pyrethroid pesticide were mostly kept at 68¹20%,The relative standard deviation?RSD?of the recovery results is less than 11%,and the indicators meet the methodological requirements of pesticide residue analysis in tea.2.Prepared by precipitation polymerization of oleic acid modified Fe₃O₄particles,using p,p'-DDT as template molecule,methacrylic acid?MAA?as functional monomer,Fe₃O₄particles as magnetic“core”,ethylene glycol dimethacrylate?EGDMA?as cross-linking agent,the magnetic molecularly imprinted polymer?Fe₃O₄@MIMs?of dicofol was synthesized in aqueous system under the action of initiator azobisisobutyronitrile?AIBN?,and its selective adsorption of dicofol molecular characteristics was studied.Adsorption thermodynamics study found that with the increase of dicofol starting concentration,MMIPs increased the adsorption of dicofol on the non-linear.The adsorption kinetic study showed that the saturated adsorption time was 120 min and the maximum adsorption capacity was 16.79 mg/g;Scatchard analysis showed that the binding sites of the MMIPs were not uniform and that there were two types of binding sites.It was confirmed by adsorption competitive test that the MMIPs could selectively identify dicofol and effectively exclude the interference of structural analogues.The results of adsorption repeatability test showed that the MMIPs still had a high selective adsorption capacity after repeated 5 times,and the adsorption capacity was only 22.70%.3.The synthetic MMIPs were applied to the separation and analysis of dicofol and pesticide residues in tea,and the method was validated,In the concentration range of 0.1².0mg/L,dicofol has a good linear correlation,the correlation coefficient is 0.9996.The method of LOD and LOQ were 0.0021 ng and 0.0071 ng,the recovery rate was 73.00%,and all indexes met the standards and requirements of pesticide residue analysis.MMIPs adsorption of tea dicofol pesticide desmutation rate reached 60%,indicating that the MMIPs as a separation material of dicofol in the tea is feasible.