Application Of Novel Nano-magnetic Surface Molecularly Imprinted Polymer Based On VBA As Monomer In Chloramphenicol Residue Analysis

Chloramphenicol（CAP）is a broad-spectrum antibiotic with excellent antibacterial properties,which has been widely used in animal husbandry and aquaculture.However,due to its serious toxic and side effects,cap residues in animals will reach human body through the food chain,causing harm to human body.Since 2002,China has stipulated that cap residue limit in animal derived food should not be detected,that is,"zero permissible quantity".However,due to its good antibacterial efficiency and low price,chloramphenicol is still used in aquaculture and animal husbandry.Therefore,it is of great scientific significance and practical value to prepare an efficient and simple method for cap detection.Molecular imprinting technology（MIT）is a technology developed on the basis of simulating the mutual recognition mechanism between enzyme and substrate in nature.It has three representative characteristics of high specificity,wide application and structure-activity prediction,and can be reused without losing selectivity.Due to its effective universality for most target analytes,it is widely used in many fields,such as medicine,chemical materials,food,environment and so on.In this project,magnetic molecular imprinting technology was used to analyze cap residues in animal derived food.The preparation,silylation and double bond grafting of Fe₃O₄nanoparticles were optimized,the Fe₃O₄ nanoparticles were coated with Si O₂ shell and grafted with KH-570.Magnetic surface molecular imprinting materials（MMIPs）with selective adsorption for cap were prepared by using cap as template molecule,VBA as functional monomer,DVB as crosslinker and AIBN as initiator.The prepared MMIPs were characterized by IR,VSM,TEM,TGA and dynamic laser particle size analyzer.The adsorption kinetics,isothermal adsorption and selectivity of MMIPs were characterized by UV spectroscopy.In order to verify the accuracy and sensitivity of the prepared MMIPs for the detection of cap residue,chicken was used as the test sample,and the methods of MMIPs and GB/T 22338-2008 were used to compare the recovery,precision and detection limit of the two methods.The results show that MMIPs have Fe-O vibration absorption peak at 570 cm^-1,Si-O vibration characteristic peak at 1098 cm^-1,C=O stretching vibration absorption peak at 1720cm^-1,C-H vibration absorption peak at 2974 cm^-1,1490 cm^-1 and 1590 cm^-1 The results show that the functional monomer VBA is successfully connected to the surface of the magnetic nanoparticles by crosslinking polymerization,and the adsorption of VBA on the surface of the magnetic nanoparticles is enhanced Fe₃O₄@Si O₂ Molecularly imprinted polymer shell was formed on the surface.TGA results showed that compared with the control group Fe₃O₄@Si O₂,the weight loss rate of MMIPs increased by about 13%,indicating that the molecularly imprinted membrane accounted for about 13%of the total weight.VSM characterization shows that MMIPs have good saturation magnetization.TEM and particle size characterization showed that the MMIPs were spherical or quasi spherical with uniform particle size distribution.The results of adsorption kinetics,isothermal adsorption and selectivity experiments showed that the prepared MMIPs had stable adsorption performance for cap and could distinguish similar drugs（FF and TAP）.The results showed that there was a good linear relationship between MMIPs and GB/T 22338-2008,and there was no significant difference in the limit of quantitation and recovery rate,which provided a basis for the application of MMIPs in the detection of actual samples.The surface molecularly imprinted magnetic Fe₃O₄ nanoparticles were silanized to prepare MMIPs.The cap residues in animal derived food were detected by liquid chromatography-mass spectrometry（LC-MS/MS）.The particle size distribution is uniform,the coating rate is good,the adsorption magnetism is high and the selectivity is good.Nano magnetic surface molecularly imprinting technology has the advantages of simple operation,easy preparation,low cost and environmental friendliness,which provides a new idea for sample pretreatment in veterinary drug residue detection.