Fabrication,Characterization And Application Of Novel Ionic Liquid-improved Solid Phase Microextraction Coatings

Solid phase microextraction（SPME）is a new sample pretreatment technique.It has attracted much attention because of its high efficiency,low solvent consumption,and easy combination with other instruments.Although some commercial coatings are available now for pretreatment of samples,they show some short comings such as low extraction efficiency and low stability.As the coatings determine the stability,selectivity and extraction efficiency of SPME,the preparation of new coatings suitable for different analyts is very important.Ionic liquids（ILs）,known as molten salts,are a class of nonmolecular solvents.They have been widely used in separation and analysis due to their advantages of non-volatile,stable,good dissolving ability and high electrical conductivity etc.By combining ILs with porous materials（e.g.conductive polymer,carbon materials,metal organic framework）,better composite coatings may be obtained.Thus they can be more widely applied in environment,food and biological analysis,etc.In this dissertation,a systemic study on the fabrication,characterization and application of IL based SPME coatings is carried out.The main content and results are as follows:1.A novel poly（3,4-ethylenedioxythiophene）-ionic liquid composite coating.for the headspace solid-phase microextraction and gas chromatography determination of several alcohols in soft drinksA PEDOT-IL composite coating was prepared by electrochemical deposition in ACN solution containing[HeMIM]NTf2.The obtained coating was porous,and it had large surface area.And with the introduction of IL,the coating presented improved thermal stability,lifetime and extraction efficiency.Coupled with GC analysis,the PEDOT-IL based fiber was used for the determination of several high boiling point alcohols and it showed lower detection limits and higher sensitivity.In addition,it had advantages of easy preparation,structure and thickness controllable and low cost.So,the PEDOT-IL based fiber had potential application as an effectiveand useful extraction tool.2.Fabrication of poly（3,4-ethylenedioxythiophene）-ionic liquid functionalized graphene nanosheets composite coating for headspace solid-phase microextraction of benzene derivativesA PEDOT-ILG composite coating was prepared by electrochemical deposition.The obtained PEDOT-ILG coating presented porous folded and wrinkled structure,and has high thermal stability（up to 340 ℃）,long lifetime（could be used for more than 200 times）.The coating had good selectivity for benzene derivatives,which was due to the combination interaction of π-π and hydrophobic effect between the coating and analyte.Owing to the synergetic effect of porous PEDOT and rich electron stacking ILG,the PEDOT-ILG coating displayed higher extraction efficiency for benzene derivatives when compared with PEDOT and commercial coatings.3.Ionic liquid polymer functionalized carbon nanotubes-doped poly（3,4-ethylenedioxythiophene）for highly efficient solid-phase microextraction of carbamate pesticidesA new Nafion-modified PEDOT-PIL/MWCNTs coating was fabricated by electrochemical method and dipping,then it was used for direct immersion solid-phase microextraction in complex matrix.It showed high thermal stability and durability.The coating exhibited much higher extraction efficiency than PEDOT and commercial coatings for carbamate pesticides.The results showed that Nafion membrane had both pollution resistance capacity and good adsorption capacity,and the introduction of Nafion membrane did not decrease the rate of mass transfer.Then it was applied for the enrichment and analysis of trace carbamate pesticides from fruit and vegetable samples in combination with GC-FID.4.Fabrication of MOF/IL composite material for the headspace solid-phase microextraction and gas chromatography determination of anilinesTo make full use of acid IL and porous MOFs,ILs supported on MOFs was prepared by immersion method,then it was used for adsorption of aniline compounds.Then we discussed the influence of the amount of IL on structure,morphology and adsorption capacity of the composites.Among various kinds of composite materials,Co-MOF/20%IL had the highest extraction efficiency.When compared with Co-MOF coating,extraction efficiency increased by 1-3 folds.The improved adsorptive performance could be explained by the acid-base and π-π interactions between the acidic ionic liquid and basic anilines.The resulting coating was successfully applied for the detection of anilines in environmental water samples.Furthermore,this study provided a new way for preparing highly porous adsorbents for the efficient adsorption of various compounds.5.In situ solvothermal growth of metal-organic framework-ionic liquid functionalized graphene nanocomposite for highly efficientenrichment of chloramphenicol and thiamphenicolA novel SPME fiber was fabricated by in situ solvothermal growth of MOF-5/ILG composite on etched stainlesssteel wire.It possessed good crystal shape and its structure was not disturbed by the introduction of ILG.The strong covalent bond interaction between MOF-5 and ILG endowed MOF-5/ILG coating with high mechanical stability and durability.Besides,the MOF-5/ILG composite also showed high adsorption capability and good reproducibility due to the synergetic effect of porous MOF-5 and ILG.Its application feasibility was tested by performing HS-SPME of trace CA and TA in food and biological samples prior to GC-FID analysis.6.A poly（ethylenglycol）functionalized ZIF-8 coating prepared by coordination-based post-synthetic strategy for the enhanced adsorption of phenolic endocrine disruptors from waterA porous PEG-NH₂ functionalized ZIF-8 coating was successfully synthesized by a facile coordinate based PSM strategy in methanol solution.The experiments demonstrated that the reaction time and temperature were crucial for the ZIF-8/PEG-NH₂ coating formation.The results showed that the optimum condition was 60 ℃ and 3 h.The coating presented high adsorption rate and adsorption capacity（0.07 mg/g）for 4-nonylphenol.Thus,it was successfully applied for the detection of 4-nonylphenol in environmental water samples.Besides,the ZIF-8/PEG-NH₂ coating possessed good stability and reusability.The proposed coordinate based PSM strategy offered an efficient and simple strategy for the preparation of functionalized MOFs membrane with low cost and good performance.