Preparation Of ?-Lactam Antibiotic Multi-Template Molecularly Imprinted Magnetic Composite Material And Its Environmental Analysis Application

Beta-lactam antibiotics(BLAs)are a class of broad-spectrum antibiotics,which are widely used in the prevention and treatment of diseases caused by various bacterial infections in humans and animals.Because it cannot be completely absorbed and decomposed by the human body or animals,it will remain in some animal products and the environment,thereby directly or indirectly causing harm to the organism and the environment.In addition,due to the residues of BLAs in the environment are often trace levels,it is necessary to study new materials for rapid separation and extraction of BLAs and to develop new methods for sensitive and accurate detection of BLAs.This paper uses surface molecular imprinting technology to prepare a ?-lactam antibiotic multi-template molecularly imprinted magnetic composite material to achieve simultaneous recognition,separation and removal of amoxicillin(AMOX),cefalexin(CFX),and cefazolin(CFZ),penicillin G(PENG)and oxacillin(OXA).In addition,the magnetic composite imprinted polymer was used as a solid-phase extraction agent,and the high-performance liquid chromatography alone and the combined dispersion liquid-liquid microextraction and high-performance liquid chromatography were used to establish two new methods for rapid detection of trace AMOX,CFX,CFZ,PENG,OXA in environment.The main research content mainly includes the following points:(1)Graphene oxide(GO)was prepared by modified Hummer method;GO was hybridized with multi-walled carbon nanotubes(MWCNTs)by esterification to form three-dimensional carbon-based materials(GO-MWCNTs);by co-precipitation,magnetic particles are loaded on The surface of the hybrid carbon-based material forms a magnetic carbon-based material(GO-MWCNTs/Fe3O4);the surface of GOMWCNTs/Fe3O4 was covered with a layer of silicon dioxide to form a magnetic carbon-based silicon dioxide by the hydrolysis of ethyl orthosilicate Composite material(GO-MWCNTs/Fe3O4/Si O2).Taked AMOX,CFX,CFZ,PENG and OXA together as templates.Respectively used GO-MWCNTs/Fe3O4/Si O2,3-aminopropyltriethoxysilane(KH550),ethyl orthosilicate,methanol as carriers,functional monomers,crosslinking agents,solvents.Using sol-gel technology for surface molecular imprinting at room temperature,and synthesizing beta-lactam antibiotic multi-template magnetic molecularly imprinted polymers(MIPs)through orthogonal optimization.Using field emission scanning electron microscopy,field emission transmission electron microscopy,Fourier infrared spectroscopy,X-ray diffraction analysis,magnetic intensity analysis and thermogravimetric analysis,a series of characterization of MIPs were carried out to analyze the physical and chemical characteristics of materials.(2)The adsorption performance of MIPs was explored,including p H influence,adsorption kinetics,adsorption isotherm,adsorption thermodynamics,adsorption selectivity and material reusability.It was found that when the p H was 5.5,the adsorption effect of the material on the five BLAs was the best.The adsorption could reach equilibrium within 60 minutes,and the saturated adsorption capacity for the five BLAs were 4.57-24.55 mg g-1.The adsorption process conforms to the pseudosecond-order adsorption kinetic model and Freundlich model.It is a process of entropy increase,endothermic,and spontaneous progress,and it is a favorable adsorption dominated by physical adsorption.The adsorption selectivity of AMOX,CFX,CFZ,PENG and OXA relative to CFR(cephalosporin)and AMP(ampicillin trihydrate)can reach the largest partition coefficients of 57.63 and 64.67,respectively,and the largest relative imprinting coefficients can reach 19.87 and17.65,respectively.In addition,after repeated adsorption-desorption-resorption of MIPs for 5 times,the total adsorption capacity was only reduced by 12%,indicating that the material has good reusability.(3)Take MIPs as solid-phase extraction adsorbents,the type and volume of eluents,extraction time,p H influence,and elution time were optimized.When p H was 7,the extraction time was 45 min,the eluent was a methanol-acetone mixed solution with a volume ratio of 3:2,the eluent volume was 4m L,and the elution time was 30 min,the effect of solid phase extraction was the best.a new method(MIPsSPE-HPLC)for the separation,enrichment and detection of BLAs in water environment was established.This method had a linear detection range of 1-50?g/L for AMOX and CFX,and a linear detection range of 1-100 ?g L-1 for CFZ,PENG and OXA.For five BLAs,the LODs(S/N=3)and LOQs(S/N=10)were 0.24-0.56 ?g L-1 and 0.81-1.88 ?g L-1,respectively.The method was applied to environmental water sample.AMOX could be detected in lake water,pond water and dairy farm wastewater,CFX and CFZ could be detected in river water and dairy farm wastewater,and PENG and OXA could be detected in all samples.In addition,the spike recovery test showed that the recoveries and relative standard deviations of the five BLAs were between 91.3% to 110.1% and 0.76% to 5.4%,respectively.(4)On the basis of solid-phase extraction,combined dispersion liquid-liquid microextraction was used to further separate and enrich BLAs.The conditions of the dispersion liquid-liquid micro-extraction of BLAs were optimized.2 m Lof the eluent was used as the sample and it was found that the dispersion liquid-liquid microextraction effect was best when tetrachloroethane was used as the extractant,the extractant volume was 50 ?L,and the salt concentration(Na Cl mass fraction)was1%.A new method(MIPs-SPE-DLLME-HPLC)was established for the detection of BLAs in water by MIPs solid-phase extraction-dispersive liquid-liquid microextraction-high performance liquid chromatography.The linear detection range of five BLAs after being enriched by this method was 1-200 ?g L-1,the correlation coefficient is between 0.993 and 0.998,and the LODs(S/N=3)and LOQs(S/N=10)were 0.01-0.04 ?g L-1 and 0.03-0.13 ?g L-1,the theoretical enrichment factors for AMOX,CFX,CFZ,PENG and OXA are 342,354,127,187,207(If all the SPE eluent was used for dispersion liquid-liquid microextraction,the enrichment factors could be doubly enhanced and the LOD decreased by half),and through comparative analysis with other BLAs determination methods,this method had low detection and quantification limits,relatively high enrichment multiples,and a wide linear detection range.