Separation And Enrichment Of New Organic Pollutants By Solid Phase (Micro) Extraction Using Porous Micro/nano Materials

Environmental analytical chemistry includes sample collection and pretreatment,sample analysis and calculation of analytical results.The sample pretreatment technology is one of the difficulties and hot topics of current environmental analysis field.In recent years,some new,safe and reliable pretreatment technologies,which are environment friendly and low-cost,such as solid phase extraction?SPE?,solid phase microextraction?SPME?and magnetic solid phase extraction?MSPE?has been developed deeply and applied widely.As the core of sample pretreatment technology,the selection of adsorption?medium?materials with high selectivity and strong enrichment ability has become a hot topic at present.New micro/nano materials,such as porous graphene,metal organic framework and their composites with the advantages of environment friendly,novel structure,large specific surface area,uniform pore size,controllable pore size,modifiable surface of material and stabilized physical chemistry properties,which has received great attention since its many advantages,especially in the field of sample pre-treatment technology,which show inestimable prospect.In this paper,three new porous micro-nano materials were designed and prepared as adsorption materials for solid phase extraction?SPE?and solid phase microextraction?SPME?to separate and enrich new organic pollutants in environmental samples,and combined with the high performance liquid chromatography?HPLC?to analysis and detect these new organic pollutants.This paper consists of the following four chapters:Chapter 1:This chapter summarized the importance and research progress of sample pretreatment technology in modern environmental pollution analysis.Then it focused on the core position and research status of adsorbent materials in sample pretreatment technology,as well as the research and application in the field of adsorption and separation of environmental pollutants.Chapter 2:A three-dimensional porous graphene sponge?GS?was prepared by freeze-drying method,then the as-synthesized nanocomposites are characterized by fourier transform infrared spectroscopy?FT-IR?,powder X-ray diffraction?XRD?,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,N₂adsorption-desorption isotherms.The results show that the prepared material?GS?has a uniform porous micro-nano structure,which is beneficial to the adsorption of the target compound.It is used as a solid phase extraction?SPE?adsorbent and combined with high performance liquid chromatography?HPLC?to determine six ultraviolet filters in different types of cosmetics,the results show that the method is facile,low-cost,rapid and sensitive.Chapter 3:A nitrogen-doped three-dimensional porous composite micro/nanomaterial?ZIF-8/GOS?was prepared by one-pot method combined with directional freeze-drying and high temperature carbonization at 800?,and the as-synthesized nanocomposites are characterized by scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,fourier transform infrared spectroscopy?FT-IR?,powder X-ray diffraction?XRD?,N₂ adsorption-desorption isotherm,the results show that the composite has a three-dimensional porous network structure,and large specific surface area and uniform pore size distribution.Based on this,a method using ZIF-8-GOS for solid phase extraction?SPE?-high performance liquid chromatography?HPLC?was established for the analysis of five sex hormones in milk and milk products.The results revealed satisfactory recoveries and sensitivities at trace level,with detection of some of the target compounds,which demonstrates the good application potential of the ZIF-8-GOS adsorbent in the trace analysis of organic contaminants.Chapter 4:MAF-5 and MAF-6?Zn?with good stability,high porosity,adjustable pores and hydrophobic surfaces were prepared via a rapid synthesis method,then the as-synthesized nanocomposites are characterized by scanned electron microscope?SEM?,fourier transform infrared spectroscopy?FT-IR?,powder X-ray diffraction?XRD?,N₂ adsorption-desorption isotherms,thermogravimetric analysis curves?TGA?.The results show that MAF-6?Zn?has more excellent adsorbent properties.MAF-6?Zn?was coated onto the inner and outer surfaces of the capillary by chemical bonding using silane coupling agent on the basis of a quartz capillary column,then a in-out-tube double-coated SPME fiber formed,which was used to the extraction and enrichment of sixteen polycyclic aromatic hydrocarbons?PAHs?from environmental water samples and different dairy products,and orthogonal array design?OAD?was used to optimize extraction conditions.Compared to in-tube and other types of solid-phase microextraction fibers,self-made fiber has a double enrichment ability due to the in-out-tube double-coated,which greatly enhances the efficiency of extraction.Theexperimentalresultsshowthatthemethodof MAF-6-SPME-HPLC-FLD has low detection limit,wide linear range and good repeatability.The proposed method is expected to have potential applications in the areas of environmental monitoring,emerging contaminants?ECs?,new persistent organic pollutants?POPs?,etc.