Preparation Of Magnetic Molecularly Imprinted Polymers And Its Application In Malachite Green Detection

The ordinary detection methods for malachite green(MG)in aquaculture usually exist the weaknesses of multiple steps and complicated operations in sample pretreatment.In order to simplify the detection process,the preparation of two magnetic molecularly imprinted polymers(MMIPs)for MG and its application in fish detection were researched in this study.(1)The MG-MMIPs were synthesized using Fe3O4 as magnetic nuclei,MG as template molecule through suspention polymerization.The prepared MMIPs were characterized with scanning electron microscope,fourier transform infrared spectrometer,simultaneous thermal analysis,vibrating sample magnetometer and other devices.The influence of synthesis conditions(for instance the dosages of Fe3O4,solvent,monomers,the cross linkers and so on)on the absorption capacity of the MMIPs and MNIPs were optimized.The results indicated that using MG(0.25 mmol)as template,MAA(1 mmol)as monomer,EGDMA(5 mmol)as cross linker,AIBN(100 mg)as initiator,Fe3O4(100 mg)as magnetic nuclei,PVA(W%=1)as dispersent,water(25 mL)and chloroform(5 mL)as solvents with the water bath at the temperature of 60 ?,stirring speed of 350 rpm and the synthesis time of 18 hours,the obtained MMIPs have the best absorption ability;under the optimum condition,the prepared MMIPs had amazing maximum apparent absorption amount about 5693 ?g/g,taking about 30 min to attain absorption equilibrium;the MMIPs showed strong magnetic responses,which could be fast detached from the samples with an external magnet.The prepared MMIPs were employed as the sorbent for rapidly detecting MG in fish samples combined with HPLC.The recoveries of spiked MG in fish samples ranged from 82.7%to 111%with RSD in the range of 2.0%?12.8%.When the adsorption materials were used repeatedly 5 times,the adsorption efficiency for MG also reached 90%.Thus,the prepared MMIPs could be successfully applied to the sample pretreatment for separation and enrichment of MG in fish samples.(2)The MG-MMIPs were prepared by precipitation polymerization method using MG and Fe3O4 as template molecule,magnetic nuclei,respectively.For the purpose of investigating the adsorption efficiency of the MMIPs,we optimized the synthesis conditions.The results manifested that using MG(0.25 mmol)as template,the molar ratio of MG,MAA and EGDMA was 1:8:20,AIBN(100 mg)as initiator,Fe3O4(100 mg)as magnetic nuclei,and chloroform(50 mL)as solvent with the water bath at the temperature of 60 ?,stirring speed of 400 rpm and the synthesis time of 12 hours,the obtained MMIPs had the excellent absorption ability and it only cost 5 minutes to reach adsorption equilibrium.In the solution of dichloromethane,the maximum apparent absorption amount of the prepared MMIPs was about 6190 ?g/g.The saturation magnetization of the MMIPs was 21.8 emu/g,and the superparamagnetism was high.The prepared MMIPs were employed as the sorbent for rapidly detecting MG in fish samples combined with HPLC.The recoveries of spiked MG in fish samples and RSD were 94.0%?115%,and 2.7%?12.0%,respectively.In conclusion,the MMIPs synthesized through suspention polymerization and precipitation polymerization both could be used to efficiently enrich and separate MG in fish samples pretreatment to assure the method of detecting MG was accurate and reliable.