Preparation Of Metal Organic Frameworks Material And Its Application In Detection Of Sulfonamides Residues

Sulfonamides(SAs),as a broad-spectrum synthetic veterinary antibacterial,are widely used in the prevention and treatment of livestock and poultry diseases.However,sulfonamides are prone to drug resistance and crystallize in urine,causing nephrotoxicity.Unreasonable clinical use will easily lead to the residue of SAs in animal food,which will cause great potential harm to food safety and human health.Therefore,it is urgent to quantitatively analyze and detect SAs residues in animal-derived foods.However,due to the complexity of animal food matrix,it may interfere with the sensitivity and accuracy of drug determination,so it is necessary to carry out efficient sample pretreatment to enrich and purify drugs.Dispersive solid phase microextraction(d-μSPE)has attracted wide attention in the field of drug residue analysis because of its high efficiency and simple operation process,and the design and selection of adsorbent is an important factor affecting the results of d-μSPE.Metal framework materials(MOFs)are organic coordination polymers,which are often used as adsorbents for drug extraction and enrichment in recent years because of their high specific surface area,porosity and easy modification.Therefore,the purpose of this paper is to construct MOF-based composite materials,study its application as adsorbent in the pretreatment of samples for detection of sulfonamides residues in animal foods,and establish a d-μSPE-HPLC method to determine sulfonamides residues in animal edible tissues.1.Preparation of MOFs adsorption materials(1)Preparation of ZIF-8 and its modified materialsThe substrate MOF(ZIF-8)was synthesized by solvothermal method with zinc acetate and dimethyl imidazole as metal sources and organic ligands,and then the modified ZIF-8 adsorbent was synthesized by using organic polymer compounds(sodium dodecyl sulfate,octadecylamine,poloxamer)as modifying materials.The materials were characterized by scanning electron microscope(SEM),X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(FTIR),and the results showed that the materials had the infrared characteristic peaks corresponding to the chemical groups of zeolite imidazole.Sulfamethoxazole(SMZ)was selected as the template of sulfonamides for adsorption test.The adsorption capacity of B@ZIF modified by poloxamer was 31.01mg/g,that of E@ZIF modified by octadecylamine was 36.74 mg/g,that of S@ZIF modified by sodium dodecyl sulfate was 48.75 mg/g,and that of ZIF-8 was only 18.75mg/g.The results showed that the adsorption capacity of SMZ was increased by adding surfactant to modify ZIF-8,among which S@ZIF had the best adsorption performance,and S@ZIF was selected for the subsequent adsorption test.(2)Preparation of UIO-66 and its modified materialsIn this paper,firstly,2-aminoterephthalic acid was used as organic ligand and zirconium dichloride octahydrate was used as metal source,which was dissolved in N-N dimethylformamide solution,and bulk MOF(UIO-66)was synthesized by solvothermal method.Then,metal Zn was used to modify it,and the modified adsorbent Zn@UIO-66 was synthesized.SMZ was used as the template of sulfonamides,the adsorption capacity of SMZ was 32.5 mg/g.Secondly,the adsorbent was characterized by scanning electron microscope(SEM),X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(FTIR).Scanning electron microscope images show that UIO-66 presents a spherical shape consistent with the literature report,while the modified Zn@UIO-66 presents a floral shape.The modified material changed the regular morphology of the original UIO-66,which may provide larger adsorption specific surface area and active sites for the target analyte.The infrared spectrum has the characteristic peak of UIO-66 which is consistent with the literature report and the characteristic peak modified by Zn,which also proves the successful synthesis of the material.2.Determination of sulfonamides residues in pig tissues by d-μSPE-HPLCTwo kinds of metal-organic framework materials,S@ZIF and Zn@UIO-66,were used as adsorbents for d-μSPE,and the pretreatment method of sulfonamides samples was established.(1)S@ZIF as d-μSPE adsorbent of sulfonamidesSamples were extracted with ethyl acetate and anhydrous sodium sulfate.The extraction solution was dried by nitrogen,and redissolved by methanol.Then the solution was purified by d-μSPE with S@ZIF as adsorbent,and eluted by 10%ammoniated methanol and detected by HPLC.The detection limits and quantitative limits of seven sulfonamides(Sulfamethoxazole,Sulfisoxazole,Sulfamethoxydiazine,Sulfamerazine,Sulfamethazine,Sulphadiazine and Sulfadiazine sodium)in pig muscle,liver and kidney was 10 μg/kg and 20 μg/kg,the linear correlation coefficient of standard curve was above 0.9900.The recovery rate was 64.9%～83.2%% and the relative standard deviation was less than 12% at the concentration of 20g/kg,100μg/kg and 200μg/kg.A d-μSPE method based on S@ZIF was developed,which can be used to extract sulfonamides from edible tissues of pigs.(2)Zn@UIO-66 as d-μSPE adsorbent of sulfonamidesSamples were extracted with ethyl acetate and anhydrous sodium sulfate.The extraction solution was dried by nitrogen,and redissolved by methanol.Then the solution was purified by d-μSPE with Zn@UIO-66 as adsorbent,and eluted by 5%ammoniated methanol and detected by HPLC.The detection limits and quantitative limits of seven sulfonamides in pig muscle,liver and kidney was 10μg/kg and 20 g/kg,the linear correlation coefficient of standard curve was above 0.9900.The recovery rate was64.5%～81.9%,and the relative standard deviation was less than 14%.A d-μSPE method based on Zn@UIO-66 was developed,which can be used to extract sulfonamides from edible tissues of pigs.