Preparation And Recognition Ability Of Two Malachite Green Molecularly Imprinted Polymers

Malachite green?MG?is a kind veterinary drug prohibited during the aquaculture.The ordinary detection methods for malachite green have the disadvantages of complicated pretreatment,cockamamie and time-consuming operation.For the purpose to simplify the detection procedure,the preparation and the absorption ability of two malachite green molecularly imprinted polymers?MIP?were proposed in this dissertation.This dissertation consists of four chapters:In chapter 1,the application,hazard and detection method of malachite green residue in aquatic products were reviewed.The principle of molecularly imprinted technology,preparation methods and application of MIP were also introduced.In chapter 2,the molecularly imprinted polymers were synthesized using malachite green as template molecule through bulk polymerization.The influence of polymerization conditions?such as the kinds,dosages of monomers and the cross linkers,the concentrations of template,polymerization time and so on?on the absorption ability of the polymers were optimized.Then the thermo-stability and the structure of polymers were analyzed.The result showed that according to the absorption amount and the imprinted factor the optimum polymerization condition was as follows:malachite green?0.15 mol/L?as template,azodiisobutyronitrile as initiator?0.05 mol/L?,MAA as monomer,and EDMA as cross linker,the ratio of MG,MAA and EDMA was 1:4:20 with the water bath at the temperature of 60 ^oC and the polymerization time of 18 hours.Following the conditions the prepared polymers had astonishing absorption amount about 1706?g/g MG in the solution of acetonitrile?80 mg/L?,costing about 25 min to reach absorption equilibrium.In addition,the polymers behaved high recognition ability as evidenced by its imprinted factor(Q_MIP/Q_NIP)as large as 3.6.In chapter 3,The MIP-SPE cartridges using the MIP prepared in chapter 2 as packing material were prepared and were employed in the pretreatment for the detection of MG residue in fish and shrimp.Under the optimum condition with acetonitrile as flushing agent,the mixture of methanol and acetic acid?9:1,v/v?as elute,the MIP-SPE cartridge can effectively enrich malachite green in fish and shrimp with the recovery over 80%.In chapter 4,the molecularly imprinted polymer microspheres were synthesized using malachite green as template molecule through precipitation polymerization.The influence of polymerization conditions?such as the kind of solvent,the dosage of monomer?MAA?and the cross linker?TRIM??on the absorption ability of the polymers were explored.The morph and structure of the microspheres were characterized.The result illustrated that using 0.25 mmol MG as template,1.5 mmol MAA as monomer,2.5 mmol TRIM as cross linker and 20 mg AIBN as initiator,40 mL acetonitrile as solvent,the prepared microspheres were 1.07?m in the average grain diameter.The polymer microspheres had the more excellent absorption ability than the bulk-polymerization polymers which was confirmed by the values of absorption amount?as high as 2000?g/g?and of the imprinted factor?over 4.0?in the MG solution of acetonitrile?80 mg/L?.In conclusion,in this dissertation two different methods were employed to prepare the MG-MIP whereby the MG could be efficiently enriched.It was hopeful for the prepared MIP to find its application in the pretreatment for the detection of MG residue in aquatic products.