Porous Organic Polymers-based Solid Phase(Micro) Extraction Hyphenated With HPLC For Food Safety Analysis

Food safety is one of the most concerned issues closely related to our daily life.To clarify the types and sources of pollutants in food and establish effective monitoring system are the necessary prerequisites to ensure food safety.High performance liquid chromatography(HPLC)is one of the most commonly used analytical instruments in food safety analysis.However,some problems would be encountered in practical analysis: the content of interest organic pollutants in food is lower than the instrumental detection limit,and the matrix of food is quite complex.Therefore,appropriate sample pretreatment techniques are often necessary before HPLC analysis to remove complicated sample matrix and preconcentrate interest organic pollutants.Solid phase extraction(SPE)has been widely used in food safety analysis due to the merits of high enrichment factors,low consumption of organic solvents and good reproducibility.Nowadays,miniaturized and greener SPE technologies,such as solid phase microextraction(SPME)and stir bar sorptive extraction(SBSE),have been developed to meet the requirments of practical application.For these pretreatment techniques,the adsorbent is the decisive factor on the selectivity and dynamics.Porous organic polymers(POPs)are excellent SPE adsorbents due to the merits of high specific surface area,low density and good thermal stability.Adjustable pore size and functionalization can be achieved by selecting monomers with different functional groups and different synthetic methods.The purpose of this dissertation is to explore suitable POPs for the extraction of different organics(phytohormones,pesticides and veterinary drugs),and to establish POPs-based SPE/SBSE-HPLC method for the sensitive quantification of interest analytes in food samples.The main contents of this dissertation are described as follows:(1)A melamine-based porous organic polymer(mPMF)was synthesized through solvothermal method,and employed as SPE adsorbent for inline SPE-HPLC-ultraviolet(UV)analysis of five phytohormones.The large specific surface area of mPMF could provide more adsorption sites,while melamine contributed to the rich π-electron and N-containing triazine structure for mPMF,which could form π-π interaction and intermolecular hydrogen bond with-COOH containing phytohormones.Quantitative extraction was achieved for target five phytohormones on the synthesized mPMF.The established method exhibited fastadsorption/desorption kinetics and a sample throughput of 5/h was achieved through the designed inline system.Compared with the literatures based on HPLC-UV detection system,this method presented low limits of detection(LODs)(0.06-0.11μg/L)for target phytohormones.The developed method was successfully applied for the analysis of five phytohormones in tomato juice and grape juice,with the recovery in the range of 83.1-116% and 87.2-121%,respectively.(2)Porous aromatic framework(PAF-56p)was synthesized through a Friedel-Crafts reaction,and PAF-56 p coated stir bars were prepared by adhesion method.Compared with commercial stir bars,the PAF-56 p coated stir bar showed excellent extraction performance(extraction efficiency was approximately61.8-89.5%)towards six triazine herbicides with different polarity including simazine,atrazine,ametryn,prometon,prometryne and prebane.Based on it,a method of SBSE-HPLC-diode array detector(DAD)was developed for the analysis of six triazine herbicides in maize samples.The factors affecting SBSE of target triazine herbicides were investigated by single-factor test.Under the optimized conditions,the LODs of 0.037-0.089 μg/L with the linear range within 0.1-200 μg/L were obtained for six triazine herbicides.The developed PAF-56p-SBSE-HPLC-DAD method was successfully applied for triaizine herbicides analysis in maize and maize leaf samples,demonstrating with strong resistance to matrix interference and high sensitivity in real food analysis.(3)Triazine rings-containing porous organic polymer(TCOP)was synthesized for the extraction of three non-steroidal drugs(naproxen,ketoprofen and fenbufen)with benzene rings and carboxyl groups,and TCOP coated stir bars were prepared by sol-gel method.Based on this,TCOP-SBSE-HPLC-DAD method was established for trace analysis of three non-steroidal drugs in food samples.The extraction performance of the self-made TCOP stir bar was evaluated under the optional conditions.The LODs of this method for interest non-steroidal drugs were 0.08-0.15μg/L with the enrichment factor of 62-70-fold(theoretical enrichment factor of83-fold).Compared with commercial stir bars,the TCOP stir bar exhibited higher extraction efficiency(>75%).The proposed method was successfully applied to the analysis of non-steroidal drugs in pork and pork liver samples with complex matrix,and the recoveries of 89.6-110% and 86.8-108% were obtained for the spiked pork and pork liver samples,respectively.