Preparation Of Molecularly Imprinted Polymer And Its Application In Veterinary Drug Residue Detection

With the advancement of science and technology,modern breeding technology has developed rapidly.During the breeding process of animal husbandry and fishery,animals would easily be infected by various types of viruses,causing great economic losses.The use of veterinary drugs can reduce the outbreak of animal disease,cure diseased animals,and thus produce more high-quality meat,which contributes to a huge improvement in the quality of the breeding industry.However,there are cases where the veterinary drugs are used indiscriminately,or used during the drug holiday period,and even illicit drugs are used for extra profits.The excessive use of drugs will cause toxic and side effects on animals.besides,the drugs and their metabolites will remain in the animals'bodies,which will eventually threaten the human health and cause safety problems when these animals are made into meaty foods for consumption.Some veterinary drugs will be discharged in feces,and remain in the soil or discharged into rivers,which will pollute the environment if not properly treated,and eventually hinder the healthy development of animal husbandry and aquaculture.In this study,chloramphenicol and malachite green,two banned veterinary drugs,were selected as the target substances.The molecularly imprinted polymer prepared by two different methods can be used as the pretreatment adsorption material for sample analysis.The magnetic molecular imprinting of the prepared precipitated polymerized chloramphenicol was successfully applied to the detection of milk samples.The research content and results are as follows:A magnetic molecular imprinted polymers?MMIPs?was synthesized by using the method of surface precipitation polymerization.Combined with the molecular imprinting technology,Fe₃O₄ magnetic nanoparticle was the supporter material with chloramphenicol?CAP?as template molecule,MAA as the functional monomer.MMIPs were characterized by TEM?FT-IR and VSM.The result indicated that a uniform and stable MMIPs was grafted onto the surface of Fe₃O₄ magnetic nanoparticles with a thickness of about 100nm.The synthesized MMIPs possesses good magnetism,which can be easily separated by applying an external magnetic field.The adsorption equilibrium of MMIPs for CAP adsorption was achieved in 10 minutes,and the saturated adsorption capacity was up to 30.50 mg/g.Its molecularly imprinted adsorption kinetics conforms to the multi-molecular layer adsorption model.After the sample had been reused six times,the adsorption capacity was only reduced by 3%compared with the initial one.The MMIPs demonstrates the good selectivity.When the prepared MMIPs was applied to the enrichment of samples for the detection of chloramphenicol residual in milk,the limit of detection?LOD?calculated on the basis of the CAP concentration producing a signal/noise ratio of 3:1 was 2.7?g/kg.And the limit of quantitation?LOQ?producing a signal/noise ratio of 10:1 was 10?g/kg.MMIPs has good recovery?97.3%?104.3%?and low satisfactory relative standard deviations?2.7%?4.2%?.The use of magnetic molecularly imprinted polymer as a pretreatment enrichment method for chloramphenicol in milk samples is simple,quick and sensitive.Two kinds of banned veterinary drugs chloramphenicol and malachite green were selected as the target substances,and nano-magnet particles were used as supporting carriers to prepare new molecularly imprinted polymers by self-polymerization under the basic conditions of dopamine.The preparation conditions of the two molecules were optimized in this experiment,in which the polymer was tested for adsorption and fitted with an adsorption model.Results show that the best preparation conditions of the new chloramphenicol molecular imprinting are:0.2g nano-magnet,5mg template molecule,100mg dopamine,p H=8.0 Tris-HCl buffer.The adsorption capacity of MMIPs in a solution with chloramphenicol concentration of 100 mg/L is 0.60 mg/g,which is 0.38mg/g higher than that of MNIPs.For the new malachite green imprinting molecule,the best preparation conditions are as follows:the ratio of malachite green to dopamine hydrochloride is 1:10,and the polymerization time is 3h.When the concentration of the solution is 120 mg/L,the saturated adsorption capacity of imprinted molecular polymer can reach 11.53 mg/g,and its molecularly imprinted adsorption kinetics conforms to the monomolecular layer adsorption model.The theoretical adsorption capacity calculated by the Pseudo-second-order kinetic equation is close to the experimentally measured adsorption capacity.