Preparation Of Novel Porous Organic Framework Materials And Their Applications In The Determination Of Organic Pollutant Residues In Environmental And Food Samples

Organic pollutants have been widely detected in environmental and food samples,which has posed potential hazards to ecosystems and human health.Therefore,it is necessary to establish effective analytical methods monitor the organic pollutants residues in the environmental and food samples.Due to the complex matrix of environmental and food samples and the low concentration of organic pollutants residues,it is difficult to use instruments directly to detect the organic pollutants in real samples.Therefore,the use of sample pretreatment techniques to enrich and isolate the organic pollutants from real samples is required.Compared with the traditional liquid-liquid extraction technique,the developed sample pretreatment methods such as solid-phase extraction（SPE）and magnetic solid-phase extraction（MSPE）have the advantages of low solvent consumption,easy operation and good reproducibility,and currently,they are widely used in the environmental and food analysis.An important factor that determines the extraction efficiency of SPE and MSPE is their adsorbents.Therefore,the development of new,low-cost,and high-efficiency adsorbents has become a hot topic of current research.Based on the previous research work reported in the literature,in this theses work,we designed and prepared several porous organic frameworks（POFs）as the adsorbents for either SPE or MSPE.Combined with the detection by high performance liquid chromatography（HPLC）,the new analytical methods for the determination of trace organic pollutants in environmentalal water and food samples were established.The main research contents are as follows:1.Three hyper crosslinked polymers（HCPs）（named as OPD-HCP,MPD-HCP and PPDHCP）were synthesized via Friedel-Crafts reaction by using o-phenylenediamine（OPD）,mphenylenediamine（MPD）and p-phenylenediamine（PPD）as monomers.Among them,MPD-HCP showed the best adsorption performance for the five nitroimidazoles（NDZs）（metronidazole,ronidazole,secnidazole,dimetridazole and ornidazole）.It was used as SPE adsorbent in combination with high performance liquid chromatography-ultraviolet detection（HPLC-UV）for the determination of the NDZs in environmental water,peach juice,honey tea and honey samples.Under the optimized conditions,the linear response was in the range of 0.07-40.0 ng mL^-1 for environmental water,with the method recoveries of 86.8%-113.3%,the limits of detection of 0.02-0.15 ng mL^-1 and the relative standard deviations of less than 8.1%.The method also achieved the effective determination of the NDZs in peach juice,honey tea and honey samples.Based on the experimental results and density functional theory calculations,it was demonstrated that the MPD-HCP adsorbed the NDZs through hydrogen bonding,polar and electrostatic interactions.This method provides a new option for the determination of the NDZs in real samples.2.Three magnetic covalent organic frameworks（named as M-TpPa-SO₃Na,M-TpPaSO₃H and M-TpPa）were synthesized by the solvothermal synthesis method with 1,3,5triformylphloroglucinol（Tp）and 2-sulfo-1,4-phenyl enediamine（Pa-SO₃H）or pphenylenediamine（Pa）as monomers.Among them,the M-TpPa-SO₃Na has high hydrophilicity,good magnetic responsiveness,and the best adsorption ability to some benzoylureas（BUs）insecticides.It was then explored as the adsorbent for the MSPE of the six BUs（diflubenzuron,triflumuron,hexaflumuron,teflubenzuron,flufenoxuron and chlorfluazuron）in environmental water,pear juice and honey samples.Under the optimal conditions,with the help of HPLC-UV detection,a good linearity was achieved within the concentration range of 0.27-40.0 ng mL^-1 for water sample,0.47-30.0 ng mL^-1 for pear juice sample,and 2.70-200.0 ng g-1 for honey sample.The limits of detection for the analytes were 0.08-0.11 ng mL^-1 for water sample,0.14-0.19 ng mL^-1 for pear juice sample and 0.80-1.00 ng g-1 for honey sample.The method recoveries for spiked samples were in the range of 85.0%-111.0%with the relative standard deviations less than 8.8%.The method was successfully applied to the determination of BUs in environmental water,pear juice and honey samples.3.In this study,a series of HCPs were synthesized by Friedel-Crafts acylation method to extract four auxins（indole-3-acetic acid,indole-3-propionic acid,indole-3-butyric acid and 2-naphthylacetic acid）.Among them,the QP-TC-HCP,which was synthesized with pquaterphenyl（QP）and terephthaloyl chloride（TC）as monomers,showed the best adsorption performance for the auxins.It was then explored as the SPE adsorbent to extract auxins from environmental water and peach beverage samples.Under the optimized conditions,with HPLC-fluorescence（HPLC-FLD）detection,the limits of detection were 3.0-1.0 pg mL^-1 for environmental water and 18.0-36.0 pg mL^-1 for peach beverage samples.The method recoveries of the auxins for the spiked samples were in the range of 85.0%-110.0%.The method provides a new alternative for the determination of auxins in the environment and food samples.In addition,different types of organic compounds were tested for the extraction by the QP-TC-HCP to assess its application potential and adsorption mechanism.The adsorption mechanism may be due to the polar and hydrogen bond interactions between the QP-TC-HCP and the organic pollutants.