| Pesticides and antibiotics are widely used in agricultural planting and livestock breeding.They can quickly spread to the environmental water and are long-standing without degradation,due to their good water solubility and stable chemical structure.A certain concentration of pesticide and antibiotic residues can be harmful to animals,plants and human health.Therefore,it is significantly important to establish the determination method of pesticide and antibiotic residues in environmental water samples.Magnetic graphene composite is a kind of new and potential adsorbent with convenient magnetic separation and efficient adsorption.In recent years,it has been reported that the composites are applied in environment,food and biological field.In this study,magnetic graphene composites were synthesized successfully,and applied in magnetic solid phase extraction(MSPE)for the analysis of the triazine herbicide and sulfonamide residues in water samples,coupled with high performance liquid chromatography-mass spectrometry(HPLC-MS/MS)detection.This thesis mainly includes the following points:1.Introduced the basic situation of pesticides and antibiotics,and several common sample pretreatment technologies.Emphatically expounded the overview and application of MSPE,and the research progress of magnetic solid phase adsorbent.2.An oxidized graphene based magnetic nanoparticles(GO-Fe3O4)was synthesized by one step and used as the adsorbent for the MSPE of six triazine herbicides from environmental water samples prior to HPLC-MS/MS.The synthesis material was characterized by scanning electron microscope(SEM)and fourier transform infrared spectrometer(FTIR).Various experimental parameters including the amount of GO-Fe3O4,extraction time,the p H and the ionic strength of sample solution and desorption conditions were optimized to improve the extraction efficiency.The limits of detection of the method ranged from 0.1 to 1.0 ng/L and the enrichment ranged from 616 to 902 for six triazine herbicides.The method was applied to the analysis of the actual water samples such as lake,canal and moat in Suzhou.The recoveries of the method were in the range from 85.4% to 117.6% and the relative standard deviations(RSDs)were between 1.2% and 10.0%.Attributed to its simple and rapid operation,high concentration and low detection limit,this method could be used to analyze the trace residue of triazine herbicides in water samples.3.In this study,a magnetic material based on carboxylated graphene oxide/Fe3O4nanoparticles(CGO/Fe3O4)was successfully prepared and used as the adsorbent for the MSPE of sulfonamides from environmental water samples.The magnetic material was synthesized by the modified co-precipitation method,and was characterized by SEM and FTIR.Eight sulfonamides were used as model analytes to evaluate the extraction efficiency of the as-prepared adsorbent in MSPE,and determined by HPLC-MS/MS.Several experimental factors including the amount of CGO/Fe3O4,extraction time,p H and ionic strength of the sample solution and desorption conditions were optimized to improve the extraction efficiency.Compared with GO/Fe3O4,CGO/Fe3O4 provided better adsorption and extraction abilities for the analysis of sulfonamides.Under the optimized extraction conditions,good linear relationships were obtained with correlation coefficients(r2)?0.9983.The limits of detection of the method ranged from 0.49 to 1.59 ng/L and the enrichment ranged from 1320 to 1702 for eight sulfonamides.The developed method was successfully applied to the analysis of sulfonamides in real water samples such as waste water,river water and tap water in Suzhou,China.The recoveries of the method were in the range from 83.2% to 109.2% and the RSDs were between 1.8% and 11.2%.Attributed to its simple and rapid operation,high concentration and low detection limit,this method could be applied to analyze the trace residue of sulfonamides in environmental water samples.4.Summed up the thesis and summarized the main conclusions of experiments. |
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