Solid Phase Extraction Method Based On Novel Covalent Organic Framework Materials And Its Application In Trace Pesticide Residue Analysis

Pesticides play an important role in the comprehensive control system of agricultural pests in China,but the excessive and improper use of pesticides lead to increasingly serious pesticide residue pollution,which poses a serious threat to the ecological environment and human health.It is of great significance to carry out the research of highly sensitive analysis and detection technology of pesticide residues to realize the monitoring and control of pesticide residues.In this thesis,phenoxy carboxylic acid herbicides and neonicotinoid insecticides,two pesticides widely used in agricultural fields,were selected as target pollutants,and the solid phase extraction/magnetic solid phase extraction technology was developed with covalent organic framework（COFs）materials TAPA-TFPB-COF and Fe₃O₄@PyTTA-DHPA-COF as adsorbents.An efficient method for the determination of trace pesticide residues in environmental water samples and food samples was established by high performance liquid chromatography tandem mass spectrometry（HPLC-MS/MS）.Specific research contents are as follows:1.TAPA-TFPB-COF were prepared at room temperature and used as adsorbent for solid phase extraction to extract 6 phenoxy carboxylic acid herbicides from environmental water samples,and then determined by HPLC-MS/MS.TAPA-TFPB-COF were characterized by scanning electron microscopy,X-ray diffraction spectroscopy,X-ray photoelectron spectroscopy,Fourier transform infrared spectroscopy and N₂adsorption-desorption curve.A SPE-HPLC-MS/MS method for the analysis of phenoxycarboxylic acid herbicides in water samples was established based on the optimization of 6 experimental parameters affecting the extraction effect.The linear range of the method was 1.00-200 ng·L^-1,the detection limit was low(0.08-0.28 ng·L^-1),and the reproducibility was good（intra-day and intra-day relative standard deviations were3.72%-5.30%and 2.02%-3.98%,respectively）.The established method has been successfully applied to the extraction and detection of PCAs from tap water,groundwater and surface water samples,with the recovery rate of 81.1%-112%.2.The novel Fe₃O₄@PyTTA-DHPA-COF was synthesized by solvothermal method,and characterized by transmission electron microscopy,X-ray diffraction spectrum,Fourier transform infrared spectrum,hysteresis loop test and N₂ adsorption desorption curve.A method for the analysis of 8 neonicotinoid insecticides in honey samples was established by using the synthetic material as adsorbent of magnetic solid phase extraction combined with HPLC-MS/MS technique.The effects of different extraction conditions were studied.Under the optimal conditions,the linear range of the method was good(1.00-200 ng·g^-1,R²>0.9990),the detection limit was low(0.03-0.38 ng·g^-1),and the relative standard deviations between day and day were 2.52%-4.79%and 2.47%-6.51%,respectively.The adsorbent was repeated for eight times and still had a stable and high recovery rate.The recoveries of 8 neonicotinoid insecticides ranged from 72.1%-106%with standard deviations less than 9.51%.Four neonicotinoid insecticides were found in two of the honeys at concentrations ranging from 0.93 to 4.38 ng·g^-1.