Application Of Different Sample Pretreatment Techniques To Several Toxic Pollutants In Environment

With the progress of society and the development of industry,the management of environmental pollution has received more and more attentions.In general,environmental samples have different compositions,complicated components,and many interfering substances and are influenced easily by vary environmental factors.Moreover,the concentration of the target compound is relatively low,and some sample pretreatment technologies are necessary for the subsequent instrumental analysis and determination.The traditional sample pretreatment technology generally has the disadvantages of large amount of organic solvent,long processing time,and many operation steps.These methods not only make it easy to lose samples,but also cause large errors.The use of a large amount of organic solvents can affect the health of the workers,pollute the environment,and seriously hinder the development of analysis chemistry.Therefore,the development of some new sample pretreatment methods has become one of the frontier topics in analytical chemistry.In the past few decades,various extraction methods have been developed in order to improve extraction performance and reduce overall analysis time and cost.In recent years,new sample preparation techniques such as solid phase extraction?SPE?,matrix solid phase dispersion extraction?MSPD?,microwave assisted extraction?MAE?,and dispersion liquid-liquid microextraction?DLLME?have been developed with fast extraction speed,which have the advantages of facile,low-cost,rapid and sensitive.This paper is divided into four chapters:Chapter 1:New sample pretreatment techniques such as solid phase extraction,solid phase microextraction,dispersive solid phase extraction,dispersion liquid-liquid microextraction,microwave digestion and microwave assisted extraction were summarized.The current development of matrix solid phase dispersion extraction,dispersion liquid-liquid microextraction technology and microwave digestion,as well as their detection,analysis and application of environmental pollutants were systematically introduced.Chapter 2:Three-dimensional graphene aerogels?GAs?were synthesized successfully by a simple hydrothermal reduction method and introduced as adsorbent materials of matrix solid-phase dispersion?MSPD?for the determination of six chlorophenols?CPs?in soil samples via high performance liquid chromatography?HPLC?.Fourier-transform infrared spectroscopy?FT-IR?,Raman spectroscopy?Raman?,transmission electron microscopy?TEM?,scanning electron microscopy?SEM?,powder X-ray diraction?XRD?,and N₂ adsorption-desorption transmission were applied to characterize the synthesized GAs.The characterization results show that the graphene aerogel material is a material with a highly ordered pore structure a sufficiently large specific surface area.Compared with other adsorbents and methods,GAs are more effective in CPs adsorption than commercial C18 and SWCNTs?single-walled carbon nanotubes?,and obtain the lowest LODs and good recovery.Chapter 3:In this work,a method for rapid determination of polybrominated biphenyls?PBBs?in actual water samples by ultrasonic assisted dispersion liquid-liquid microextraction?UA-DLLME?combined with high performance liquid chromatography?HPLC?was established.This section optimized the key factors affecting the extraction efficiency,including the type and volume of the extractant,the type and volume of the dispersant,the ultrasonic time,and establishe the L₁₆?4⁴?matrix through orthogonal array design?OAD?to further verify the optimization.The method was successfully applied to the analysis of environmental water samples.The method achieved satisfactory recovery?75.8%-105.2%?,high reproducibility?3.1%-6.3%?,wide linear range(0.5-1000?g·L^-1)and relatively high Enrichment factor?133-245?.Ultrasound-assisted dispersion liquid-liquid micro-extraction method combines ultrasonic extraction and simplified DLLME method,which has the advantages of rapid,high extraction efficiency,simple operation and low consumption of organic solvent.Chapter 4:A method was established for the analysis of 11 heavy metal elements?Cu,Mn,Cr,Pb,Cd,Ni,Sb,Hg,Co,Ag,As?in grain and vegetables using inductively coupled plasma mass spectrometry?ICP-MS?with microwave digestion.The microwave digestion conditions and instrumental parameters were optimized.Samples were digested completely using HNO₃-HF-H₂O₂ and HNO₃-H₂O₂.This method has the advantages of rapidness,simplicity,high sensitivity,good stability and accuracy.