Combining Pickering Emulsion Polymerization With Molecular Imprinting To Prepare Polymer Microspheres For Selective Extration Of Malachite Green

Malachite green（MG）,a triphen ylmethane dye,which was considered carcinogenic effect to the human body,has been prohibited in Chinese nationwide Aquaculture since 2002.Due to its low price and good effect of sterilization anti-parasite on the fish,malachite green was still added and used illegall y in fish breeding.GB/T 20361-2006 was issued to provide adetection method of malachite green and its metabolite.But complex steps of pretreatment including repeated extractions and rotar y evaporation restricted the range of application.Therefore,the synthesis of materials and the establishment offast and accurate pretreatmentmethod of malachite green hadreceived much attention.Therefore,it is highl y desirable to develop an effective method for fast trace detection of MG.The specific recognition ability of MIPs can be applied to solid phase extraction to achieve rapid separation and enrichment of the sample to save pretreatment time.Pickering emulsion polymerization is a surfactant free technology in recent years forMIPs s ynthesis.For the first time,this paper presents a s ystematic stud y on pol ymer microspheres（including m agnetic molecularl y imprinted pol ymers）,being prepared b y combined Pickering emulsion polymerization and molecular imprinting,to adsorb and detect MG.The adsorption kinetics and thermod ynamics are deepl y discussed and anal yz ed,so as to provide a full picture of the adsorption behaviors of the polymermicrosphereswithandwithoutthemolecular imprinting.Significantly,M IPs show promising solid-phase extraction column applications for recovering MG in a continuous extraction manner.Furthermore,M-M IP sdispla ys specific recognition and magnetism that could be moved from extracts of MG in fish samples b y external magnetic field.In chapter 2,a selective sample pretreatment procedure combining molecular imprinting technique（MIT）and solid-phase extraction（SPE）was developed for the detection of malachite green.Using MG as the template molecule,the molecularl y imprinted polymer（MIP）was prepared.MIPs was synthesized using pickering emulsion polymerizationb y combining aqueous phase（0.27 mL of methacr ylic acid was added in 0.5mL of 3M Sodium hydroxide）and oil phase（consisting of 1.728 m L of eth ylene gl ycol dimethacr ylate,10 mg of MG,0.20 m L of toluene and 20 mg of AIBN）.After polymerization at 70℃for 24h,the polymer microspheres was rinsed b y methnol to ger rid of MG.Both of MIPs and NIPs was observed b y SEM and EDX.In contrast,NIPs show a larger average particle diameter and an uneven porous surface（with roughness an d a large pore size）,causing lower adsorption selectivity to MG despite a higher adsorption capacity.The specificit y and selectivity of MIPs was measured,The relative selectivit y coefficients（K₀）of MIPs were 1.07 and 1.03 respectively.Significantly,MIPs show promising solid-phase extraction column applications for recovering MG in a continuous extraction manner.The recoveries of malachite green and leucomalachite green were 71.2%and 81.4%with 75mg MIPs.In chapter 3,the s ynthetic conditions were further optimized to obtain MIPs-1 with high selectivet y.The resulted microsphereshave smaller particle size（7³1μm）b yenhancing ultrasonic power in s ynthesis of pickring emulsions.And the ratio of MAA and EGDMA was optimized to be 6:94 to improve the specificityability of MIPs.The relative selectivity coefficient s（K₀）of MIPs-1 on basic yellow,methylene blue and Safranine O were 23.96、8.61、6.44 respectively,which is much higher than Non-molecularl y imprinted polymers（NIPs-1）.A series of adsorption studies were carried out on MIPs and malachite green respectivel y,including static adsorption,adsorption kinetics,adsorption thermod ynamics and is othermal adsorption studies.It is found that the adsorption of malachite green on MIPs-1 is in accordance with Pseudo-second-order kinetic models and high temperature is beneficial to the adsorption.Molecular imprintingsolid phase extraction column（MISPE）were prepared withMIPs-1and applied to collectmalachite green in fish sample.The method of theM ISPE-HP LC-MS for malachite green detection was developed.The recover y rate of MIPs-1 spiked with 20.0,100.0 and 200.0μg/kg standards were 64.2–69.9%,87.6-89.0%and 84.5-85.3%respectivel y with the RSD from 2.7 to 10.8%.,In chapter4,Magnetic molecularl y imprinted polymers（M-MIPs）were synthesized with Oleicacid modified Fe₃O₄ by Pickering emulsion polymerization.A series of characterization,selective absorption and Application studies were carried out on M-MIPs and M-N IPs respectively.As a result,M-MIPs exhibited excellent Magnetic propert y and selective recognition ability.The relative selectivity coefficient s（K₀）of M-MIPs on basic yellow,methylene blue and Safranine O were 3.98、1.44、1.08respectively.The average recovery rate is higher than 94%.The pretreatment time of trace malachite green in fish samples will be shortened because M-MIPs can be separated from the extract using a magnet.In this paper,a convenient,rapid method based on Molecularly imprinting technology for fast trace detection of MG was developed.Herein,molecular imprinting pol ymers with excellent performance b y Pickering emulsion polymerization have been successfully applied in solid phase extraction and magnetic extraction.