Ionic Liquid Assisted Organic Polymer Monolithic Column For Capillary Electrochromatography

Capillary electrochromatography(CEC)is a micro-scaled separation technology with high efficiency and high selectivity which is the hybrid technology of capillary electrophoresis(CE)and high performance liquid chromatography(HPLC).Capillary electrochromatography overcomes the drawback that capillary electrophoresis cannot be used for the separation of neutral analytes.Compared with packed and open tubular columns,monolithic column has advantages of simple preparation,fritless design,large column capacity and high column efficiency.It has been a hot topic in the field of capillary electrochromatography.Ionic liquid(ILs),organic molten salts,consist of organic cations and inorganic or organic anions.Due to good chemical stability and thermal stability,ionic liquids are widely used in catalytic synthesis,electrochemical detection,chromatographic separation fields.Zeolitic imidazolate frameworks is a subfamily of metal organic frameworks.They possess advantages of good porosity of metal organic frameworks and high stability of zeolites,widely used in catalysis,gas adsorption storage,drug slow release,chromatographic analysis.In this thesis,a monolithic column modified with bifunctional ionic liquid and styrene stationary phases is prepared through a single-step copolymerization;another monolithic column is prepared by an embedding method with the incorporation of zeolitic imidazolate framework(ZIF-8)in ionic liquid polymeric monolithic column.The main contents include two parts:Part ?:monolithic column modified with bifunctional ionic liquid 1-allyl-3-methylimidazolium bromide(AlMeIm+Br-)and styrene stationary phases.In this work,the monolithic column was prepared by one-step in situ polymerization with AlMeIm+Br-and styrene as monomers.Scanning electron microscopy(SEM)and Fourier transform infrared spectra(FT-IR)were used to characterize the successful synthesis of the monolithic stationary phase.The morphology was uniform and continuous with good pore structure.The imidazole-type ionic liquid contains a positively charged imidazole ring structure with anion exchange interaction.The styrene-benzene ring structure provides hydrophobicity and ?-? stacking interaction.Meanwhile,the similar conjugated structure of the imidazole ring and benzene ring is beneficial to form synergistic effect.The stationary phases achieve electroosmotic flow regulation without affecting the performance of chromatographic separation.The prepared monolithic column can successful achieve the separation of neutral substances(alkylbenzene and chlorobenzene),acidic substances and phenols in capillary electrochromatography.The highest column efficiency was 2.70×105N/m(theoretical plates,N)for toluene.The monolithic column possessed good stability and reproducibility.The combination of AlMeIm+Br-and styrene was a promising option in the fabrication of the organic polymer monolithic column.Part II:ionic liquid organic polymer monolithic column with incorporation of zeolitic imidazolate frameworks-8(ZIF-8).In this work,by embedding method,ZIF-8 was incorporated into the ionic liquid organic polymer monolithic column as stationary phases.Monolithic column ZIF-8-Poly(IL-EDMA)was prepared.X-ray diffraction(XRD)and energy dispersive analysis(EDS)were used to characterize the successful synthesis of the monolithic column.The results of Fourier transform infrared spectra(FT-IR)showed that the ZIF-8 material was successfully embedded in the ionic liquid organic polymer skeleton.The prepared monolithic column successfully achieved the separation of neutral substances,anilines and phenols.The highest column efficiency was 2.07×105 N/m(theoretical plates,N)with toluene as the analyte.The monolithic column possessed good stability and reproducibility.The successful preparation of zeolitic imidazolate frameworks-8(ZIF-8)ionic liquid organic polymer monolithic column greatly expanded the source of monolithic column chromatographic stationary phases material.