Preparation,Performance Evaluation And Optimization Of Sulfisoxazole Surface Molecularly Imprinted Microspheres

Animal derived food is an indispensable part of people’s daily diet,and drug residues in animal derived food have attracted more and more attention from all walks of life in recent years.Drug residue testing on animal derived food is an important method for drug residue control.Exploring more efficient detection technology has also become an important task of scientific research.In this paper,a new purified extractant for veterinary drug residue detection--molecular imprinted polymer was developed.Use silica microspheres as inert core,sulfisoxazole as template molecule and methacrylic acid as monomer,the pre-assembled system was simulated by quantum chemical calculation and the imprinting ratio was determined.Then,surface molecularly imprinted polymeric microspheres of sulfisoxazole（SIZ@SiO2@MIP）were prepared on the surface of microspheres by electron transfer atom transfer radical polymerization（AGET ATRP）.The adsorption properties and extraction conditions were evaluated,which provide a theoretical and practical foundation for further sample pretreatment.The results of structure characterization showed that the surface structure of SIZ@SiO₂@MIP change,the surface bulge increased and became more compact.The results of thermogravimetric analysis also showed that the weight loss of SIZ@SiO₂@MIP at 800℃was 13.4%,higher than that of silica microspheres by 4.1%,indicated the existence of molecularly imprinted layer on the surface of the microspheres.The adsorption performance of SIZ@SiO₂@MIP was evaluated,and the surface molecularly imprinted microspheres of sulfaphenazole（SPA@SiO₂@MIP）and non-molecularly imprinted microspheres（SiO₂@NIP）were prepared for comparative study.According to the adsorption kinetics,the adsorption capacity of siz on SIZ@SiO₂@MIP reached 80.04%of the equilibrium adsorption amount at 5 min,and reached the adsorption equilibrium at 30 min,while the adsorption capacity of spa on SPA@SiO₂@MIP reached79.17%of the equilibrium adsorption amount at 5 min,and reached the adsorption equilibrium at 15 min,indicated that the adsorption rate of the two MIPs on template was faster.At the initial concentration of 2 mmol·L^-1,the imprinting factor of SIZ@SiO₂@MIP was 2.41,and that of spa was 1.89.Langmuir,Freundlich and Langmuir Freundlich isotherms were used to fit the results of isothermal adsorption experiments.It was concluded that a molecularly imprinted layer was formed on the surface of silica microspheres,and the molecularly imprinted layer on the surface of SIZ@SiO₂@MIP was more uniform and more specific.On the surface of SPA@SiO₂@MIP,the heterogeneity was stronger,the pores were irregular and the adsorption performance was poor.The selective adsorption experiments show that both MIPs had certain adsorption capacity for the template molecular structure analogues,but there were some differences.Finally,the synthesized SIZ@SiO₂@MIP was filled into the SPE column as adsorbent,and the extraction conditions of the column were optimized.The results showed that the column was pretreated with 5 ml acetonitrile and 10 ml water.The loading solvent was 10%methanol water,the eluent was 1 ml water,and the eluent was 5 ml 50%methanol water solution.According to the optimized results,the regeneration performance of molecularly imprinted solid extraction column was investigated.The results showed that the recovery rate of 10 times was stable in the range of 94.28%±9.31%,and could still reach 96.46%after 10times of used,indicated that the regeneration performance was good and the performance was stable.This study provides a theoretical and practical basis for the application of surface molecular imprinting technology in the efficient detection of sulfonamides residues.