Study On The Detection Of Sulfa Antibiotics In Environmental Water By HPLC Analysis Combined With Magnetic Dispersed Solid-Phase Extraction

Since the discovery of penicillin in 1928,the process of discovering natural antibiotics has gradually entered a golden age,culminating in the1950s.Antibiotics have transformed modern medicine and dramatically increased the average human life expectancy.Among the many types of antibiotics,sulphonamide antibiotics（SAs）were the first truly clinically effective broad-spectrum antibacterial agents.SAs are a large class of synthetic antibiotics with a broad spectrum of antibacterial activity,high efficiency and relatively low cost,and are widely used in medicine,pharmaceuticals,animal husbandry and aquaculture for the prevention and treatment of a wide range of bacterial-based infections.However,most veterinary antibiotics are not fully absorbed in the animal gut and the unabsorbed portion is excreted in the form of prototypes and metabolites that are spread to the environment through runoff,compost leachate and other routes.In recent years,the overuse and misuse of antibiotics has led to residues of sulphonamide antibiotics in various environmental media to varying degrees,resulting in ongoing environmental contamination and risk of human exposure.Therefore,it is of great research value and academic significance to establish an efficient and convenient detection method for the monitoring of sulphonamide antibiotic residues in environmental media.High performance liquid chromatography（HPLC）,also known as high pressure liquid chromatography,is developed as a mobile phase with high pressure in the late 1960s by high pressure transport mobile phase,high performance column separation,high sensitivity detector detection chromatography analysis technology.Compared with classical liquid chromatography,HPLC has the advantages of high column efficiency（theoretical number of plates 10⁵/m）,high separation efficiency and high degree of automation.HPLC detector can be equipped with UV,fluorescence,electrochemical,mass spectrometry and other detectors,among which the UV detector is its universal detector.Compared with other detectors,the sensitivity of the ultraviolet detector is lower.Therefore,HPLC is often combined with sample pretreatment technology to improve the sensitivity of the detection method.The development of efficient sample pretreatment technology is mainly through the design of new materials with their own unique functional group epitopes,through hydrogen bond,hydrophobic force,electrostatic gravity and other acting forces,so as to realize the purification and enrichment of the measured objects.In this study,a new porous-covalent organic polymer-coated magnetic dispersed solid-phase extraction material was synthesized for sulfonamide antibiotic pretreatment in environmental water samples.And combined with the detection and analysis of sulfonamide antibiotics in environmental water by HPLC-UV.The proposed method has the advantages of high sensitivity,low detection limit and good reproducibility.Its main contents are:Part 1 Synthesis and characterization of magnetic nanoporous covalent organic polymers Fe₃O₄@SiO₂-NH₂-COPObjective:Magnetic nanopore covalent organic polymers（Fe₃O₄@SiO₂-NH₂-COP）were prepared as a magnetic solid-phase extraction material for detecting sulfonamide antibiotics in the environment.Method:The Fe₃O₄nanoparticles were prepared by the solvent heat method,silica was quickly modified on Fe₃O₄nanoparticles by TEOS（alkaline catalytic hydrolysis and condensation）using gel gels.The APTES was then bond-wise modified on the surface of Fe₃O₄@SiO₂by a silanylation reaction.Finally,cyanuric chloride and 1,3,5-benzenetriol were used as the shell layer of the controlled magnetic adsorption material,and the Fe₃O₄@SiO₂-NH₂surface was physically coated to form the final magnetic nanoporous covalent organic polymer Fe₃O₄@SiO₂-NH₂-COP.The prepared materials were characterized and characterized by scanning electron microscope（SEM）,transmission electron microscope（TEM）,Fourier Transform Infrared spectrum（FT-IR）,Magnetic Properties Measurement System（MPMS）,N₂porosity determination,and X-ray diffraction（XRD）.Results:The magnetic nanocovalent porous organic polymer Fe₃O₄@SiO₂-NH₂-COP was synthesized,with nanoparticle diameter exceeding 500nm,surface rougher than exposed Fe₃O₄nanoparticles,with unique microporous shell structure,large specific surface area(137.93 m²g^-1)and high saturation susceptibility(50.5 emu g^-1).Conclusion:The characterization results demonstrate the successful preparation of amorphous magnetic nanoporous organic polymers with good dispersion and simple synthesis method,providing a new choice for the enrichment detection analysis of sulfamide antibiotics in surface water.Part 2 Sulfa antibiotics in environmental water were detected by the MSPE-HPLC-UV method based on magnetic nano-porous covalent organic polymer Fe₃O₄@SiO₂-NH₂-COPObjective:The magnetic nanopore covalent organic polymer Fe₃O₄@SiO₂-NH₂-COP was used as solid phase extraction combined with high performance liquid chromatography for detection and analysis of Sulfamethazine（SM2）,sulfamethoxazole（SMZ）,sulfadimethoxine（SDM）,and sulfamethoxypyridazine（SMP）in the pond around a cattle farm.Method:Under the optimal extraction and separation conditions,the water sample was filtered and then directly used for the determination.The separation conditions and sample pretreatment conditions for HPLC were optimized using the magnetic nanopore covalent organic polymer Fe₃O₄@SiO₂-NH₂-COP.Under optimal extraction and separation conditions,water samples were used directly for detection and analysis.Results:Under optimized sample preprocessing and separation conditions,SM2,SMZ,SDM and SMP had detection limits of 0.10-0.25μg L^-1,well linear between 0.45 and 250.00μg L^-1,with the determination coefficient R²≥0.9990.The intra-day and inter-day precision were 1.9 to4.8%and 3.4 to 8.9%,respectively.The spiked recovery was 79.7 to 92.2%.Conclusion:Fe₃O₄@SiO₂-NH₂-COP magnetic dispersion solid phase extraction combined with the high performance liquid chromatography was developed to determine SM2,SMZ,SDM and SMP in surface water around a cattle farm.The synthesis method and extraction process are simple,and the method is sensitive and suitable for the analysis of sulfonamide antibiotics in surface water.