Preparation Of Novel Porous Organic Polymers And Their Applications In The Determination Of Some Pesticide Residues By High Performance Liquid Chromatography

In recent years,various pesticides have been widely used in agricultural production.Therefore,their residues in food products have become the focus of public attention.Due to the large variety of the pollutants complex sample matrix and low concentration of the target analytes in the sample,developing sensitive analytical techniques for detecting pesticide residues are necessary.The proper sample preparation method is the key to the accurate determination.Solid phase extraction（SPE）and magnetic solid phase extraction（MSPE）have become popular sample preparation techniques due to their advantages of simple operation,short extraction time and low consumption of organic solvents.Since adsorbent plays a crucial role in both SPE and MSPE,developing new adsorbents has been the focus of research in analytical chemistry.In this thesis,some porous organic polymer materials were prepared and used as the adsorbents in SPE or MSPE to extract some pesticides from food samples prior to high performance liquid chromatography or high performance liquid chromatography-mass spectrometry analysis.The research mainly involves the following:1.A covalent organic framework named TpAzo was successfully fabricated by a simple and environmentally friendly mechanochemical grinding method based on the Schiff base aldehyde-amine condensation reaction between 1,3,5-triformylphloroglucinol（Tp）and4,4′-azodianiline（Azo）,with p-toluene sulphonic acid as molecular organizer.The TpAzo was characterized by scanning electron microscopy,transmission electron microscopy,powder X-ray diffraction,N₂ adsorption-desorption isotherms and thermogravimetric analysis.The TpAzo possessed a sheet-like morphology,rich porosity and good thermal stability.The extraction performance of the TpAzo was investigated by using it as the solid phase extraction adsorbent for the extraction of benzoylurea insecticides（BUs）from juice,tomato and white radish samples prior to high performance liquid chromatographic analysis.Under the optimal conditions,a good linearity for the BUs existed in the range of1.0-160.0 ng mL^-1 for juice sample and 0.5-80.0 ng g^-1 for tomato and white radish samples with the correlation coefficients of 0.9956-0.9999.The limits of detection for the analytes were 0.1-0.2 ng mL^-1 for juice sample and 0.05-0.1 ng g^-1 for tomato and white radish samples,and the method recoveries for the analytes fell in the range of 84.1%-108.6%.The adsorption mechanism of the TpAzo was investigated by using it to extract different types of organic compounds,including phthalates,phenylurea herbicides,and carbamate insecticides.The results showed that theπ-stacking and hydrophobic interactions between the TpAzo and the analytes played an important role for the adsorption.2.A solid phase extraction（SPE）method with an o-hydroxyazobenzene-based organic polymer as adsorbent was established for the extraction of five carbamate pesticides（metolcarb,carbaryl,isoprocarb,bassa and diethofencarb）from milk,white wine and juice samples.The main factors affecting the SPE were optimized,including sample volume,sample loading rate,sample solution pH,desorption conditions and cartridge reusability.Under the optimal conditions,a good linearity existed in the range from 1.0 to 320.0 ng mL^-1 for milk and white wine samples and 0.5 to 160.0 ng mL^-1 for juice sample with the correlation coefficients between 0.9956 and 0.9998.The method recoveries of the carbamates were 82.0%-110.0%.The limits of detection were 0.12-0.40 ng mL^-1 for milk and white wine samples,and 0.06-0.20 ng mL^-1 for juice sample.The adsorption mechanism of the adsorbent was investigated by the extraction of different types of organic compounds（carbamates,benzoylurea insecticides,endocrine disrupting chemicals and polycyclic aromatic hydrocarbons）with the adsorbent.The results showed that the existence of the hydrogen-bonding between the adsorbent and the analytes is favorable for the adsorption,but strong hydrophobicity seems to have an adverse effect.3.Magnetic porous organic polymer composites（MOPs）were synthesized in aqueous solution by an environmentally friendly method.A new magnetic solid phase extraction（MSPE）method using the MOPs as the adsorbent was established to extract phenylurea herbicide（methicone,chloromeron,isoproturon and monolinuron）from juice samples.Under the optimal conditions,the linear range of the real samples were 1.0-160.0 ng mL^-1,the correlation coefficient was 0.9996-0.9999,and the method recovery of the four phenylurea herbicides were 90.5-107.9%.The detection limits in the sample ranged from0.1 to 0.2 ng mL^-1.4.A magnetic porous covalent triazine-based organic polymer（M-PCTP）was synthesized by coprecipitation method.The M-PCTP combined the porous properties of the PCTPs with the magnetism of Fe3O4 nanoparticles,possessing good porosity and sufficient magnetism.It was used as magnetic solid phase extraction（MSPE）adsorbent to extract some carbamate pesticides（propoxur,carbaryl,isoprocarb,fenobcarb and diethofencarb）from lemonade juice samples prior to high performance liquid chromatography-mass spectrometric detection.Under the optimal conditions,a good response linearity for the quantification of the analytes for the real samples was received from 0.1-0.6 up to 80.0 ng mL^-1 with the correlation coefficients of 0.9882-0.9983.The method recoveries for the five carbamates were 86.7-106.7%.The limits of detection were 0.02-0.20 ng mL^-1 for lemonade sample.