Porous Organic Polymer-Based Stir Bar Sorptive Extraction Hyphenated With High Performance Liquid Chromatography For The Analysis Of Trace Endocrine Disruptors

Stir bar sorptive extraction(SBSE)is a new pretreatment technology with advantages of large coating amount,less solvent consumption and high recovery.It has been used for environment and food analysis.The coating plays an important role in SBSE,and commercially available stir bars are few with slow extraction kinetics presently.Therefore,developing novel coated stir bars with good thermal/mechanical stability,and fast adsorption kinetics is of great significance to improve the selectivity,the speed of analysis and reduce cost.Porous organic polymers(POPs)have the merits of high specific surface area,low density,good thermal stability,rich functional groups and pore structure.POPs can be adjusted to different pore size and functionalized by selecting suitable monomers and synthetic methods.POPs has been used in solid phase extraction,magnetic solid phase extraction and solid phase microextraction and demonstrated with the merits of high extraction efficiency and fast kinetic.While,few applications of POPs have been reported in SBSE so far.The purpose of this dissertation is to prepare POPs coated stir bar for the extraction of trace endocrine disruptors(EDCs),and to establish POPs-SBSE-high performance liquid chromatography(HPLC)method for the quantification of trace EDCs in environmental and food samples.The main contents of this dissertation are described as follows:(1)With 4,4’-diaminoterphenyl and phloroglucinol as the monomers,Azo-linked porous organic polymer(Azo-POP)was prepared by a green mild azo reaction.AzoPOP is rich in phenolic hydroxyl groups and benzene rings,which can form intermolecular hydrogen bonds with the phenolic hydroxyl groups in interest benzotriazoles(BZTs).The π-π interaction between the benzene ring and the triazole ring would promote the adsorption of target BZTs on Azo-POP.AzoPOP/polydimethylsiloxane(PDMS)coated stir bar was prepared via sol-gel technique for the extraction of target BZTs.Scanning electron microscopy(SEM)showed the coating was uniformly coated,the surface was rough,and the thickness of coating was about 125 μm.Compared with commercial PDMS stir bar,Azo-POP coated stir bar showed superior extraction efficiency(75-88% vs 45-65%)under similar conditions and kinetics(50 min vs 120 or 360 min)for six BZTs(UV-PS,UV-234,UV-320,UV-326,UV-327,UV-329).A method of stir bar sorptive extraction(SBSE)combined with HPLC-diode array detector(DAD)was developed to analyze six target BZTs.The optimization of SBSE conditions for extraction of interest BZTs was performed by single-factor test.Under the optimized conditions,the limits of detection within 0.12-0.33 μg/L were achieved for six BZTs,with the linear range within 0.5-100 μg/L.The method was applied to detect six BZTs in the East Lake water,Yangtze River water,and campus soil samples,and no target BZTs were detected.The recoveries of target BZTs in spiked samples were found in the range of 94.9-118%,96.2-118%,and 88.2-119%,respectively.(2)Cyanuric chloride and 4,4’-diaminoterphenyl were used as monomers to synthesize poly(4,4’-diaminoterphenyl-triazine)(PDT)covalent organic frameworks,and PDT coated stir bars were prepared by adhesion method.SEM showed the surface of coating was rough,the thickness of coating was about 215 μm.The rich π-electron and Ncontaining triazine structure of PDT is beneficial for the adsorption of five phthalate esters(diethyl phthalate,diallyl phthalate,dipropyl phthalate,benzylbutyl phthalate,dibutyl phthalate).Based on this,a new method of PDT-SBSE-HPLC-DAD was established for the determination of five phthalate esters plasticizers.Under the optimized extraction and desorption conditions,the detection limit of the method was 0.04-0.27 μg/L,and the enrichment factor was 54-80-fold(the theoretical enrichment factor is 83-fold)for target analytes.Compared with the commercial PDMS stir bar,the self-made coated stir bar exhibited higher extraction efficiency(> 65%)and faster extraction kinetics(50 min vs 240 min).The established method was applied to the quantification of interest phthalate esters in mineral water and liquor samples.Diethyl phthalate(1.19-2.98 μg/L)and dibutyl phthalate(0.77-0.91 μg/L)were detected in mineral water samples,and the recoveries of target analytes in spiked mineral water A,mineral water B and white spirit sample were 85.4-117%,87.4-117% and 85.4-109%,respectively.