Analysis Of Sulfonamide Residues By Magnetic Solid Phase Extraction Based On Carbon Material Coated With Fe₃O₄

Magnetic solid phase extraction(MSPE)is a new SPE technique,based on magnetic adsorbent and magnetic separation by means of an external magnet.Then the adsorbed analytes are eluted using appropriate solvents and are determined with proper techniques.Compared with other pretreatment techniques,magnetic solid phase extraction technique has merites of simple and rapid operation,recyclable adsorbent and low solvent consumption.Herein,two different magnetic composites were prepared and used as adsorbents for the MSPE of sulfonamides.Furthermore,coupling with high performance liquid chromatography-ultraviolet detector(HPLC-UV),two new detection methods for sulfonamides dairy products and meat foods were established.The main contents are as follows:A magnetic reduced graphene oxide and carbon nanotube composite was prepared by solvothermal method and characterized by scanning electron microscopy,X-ray diffraction and magnetometer.The diameter of Fe₃O₄ microparticles was about 350 nm,which were covered by carbon nanotubes and reduced graphene oxide sheets,while carbon nanotubes inserted between the reduced graphene oxide sheets effectively prevented their aggregation.The saturation magnetization values of Fe₃O₄/r GO-CNTs was 50 emu/g,which presented good magnetic property.Its adsorption property was explored and various parameters affectiong MSPE extraction were optimized,such as:adsorbent amount,extraction time,ionic strength of solution,p H,and elution conditions.Under the optimal conditions,by coupling with HPLC-UV,a new method for the extraction and detection of four sulfonamides in milk was developed.The method was simple to operate and had wide and high sensitivity.An ionic liquid([HeMIM]NfT₂)-doped magnetic reduced graphene oxide and carbon nanotube composite was synthesized by solvothermal method,its structure,morphology and magnetic property were studied by transmission electron microscopy,scanning electron microscopy,X-ray diffraction,Fourier transform infrared spectroscopy and magnetic strength.The prepared magnetic material showed good adsorption for sulfonamides,and enrichment folds were upto 325.3-386.1.Through coupling with HPLC-UV for the detection of sulfonamides,the detection linear range was 0.25-100?g/L,and the detection limits were0.029-0.083?g/L.The method was successfully applied for detection of sulfonamides in meat samples,and it presented good performance.