Preparation Of Nanoparticles-based Monolithic Columns And Their Applications In Electrochromatography

Polymer monolithic columns have been widely used in the field of separation science because of their simple preparation, convenient modification and good biological compatibility. However,due to its inherent property of a dual-pore structure in polymer-based monoliths, it is difficult to achieve high separation efficiency in the separation of small molecules. Recently, nanomaterials have been widely used in separation science especially in chromatographic solid phase and electrophoresis due to their unique advantages such as large surface area, diverse morphology and flexible structure. Incorporating nanomaterials with monothic solid phase or as nano-template is a desirable solution to improve the pore structure of monolithic columns, and thus to enhance the separation efficiency based on this motivation, we devoted to develop two different kinds of polymer-based monolithic columns by using magnetic nanoparticles as nano-template and graphene oxide(GO) as an incorporated monomer, respectively. Accordingly, their chromatographic retention mechanisms were systematically evaluated in detail. High efficiency separation of a series of small molecules can be achieved. The thesis consists of three chapters as follow:In chapter 1, the theory of capillary electrochromatography, the classification of capillary monolithic columns and their preparation method, as well as namomaterial’s property and their applications in chromatography were introduced in detail. In this part, the connection and applications between monolithic columns and materials were mainly introduced. Besides, the aim and significance of this thesis were also briefly presented.In chapter 2, preparation of Fe3O4 nanopartical-based monolithic column by in situ copolymerization of glycidyl methacrylate (GMA) and ethylene glycol dimethacrylate (EDMA) as monomers in a binary porogenic solvent (cyclohexanol and dodecanol) was described. Different ratios of monomers, porogens and Fe3O4 nanoparticals were used for optimizing the properties of monolithic column. Compared with the bare monolithic column, the nano-template column presented bettter separation and efficiency performance when separating alkylbenzenes, phenols and anilines.The purposed monolithic column was also applied to efficiently separate alkaloids and anaesthetics. The successful applications demonstrated that the glycidyl methacrylate based monoliths prepared by using nano-template are a good alternative for enhanced separation efficiency of small molecules.In chapter 3, GO-based monolithic column by in situ copolymerization of 3-acrylamide benzene boric acid (AAPBA) and pentaerythritol triarylate (PETA) as monomers in a binary porogenic solvent (glycol and cyclohexanol) was prepared. The ratios of AAPBA to PETA, the composition of porogenic solvent and the quantity of GO in the solvent were optimized in detail as to the column properties (e.g. permeability, morphologyand selectivity). A series of amides were used to evaluate the monolithic column performance in terms of hydrophobic, hydrophilic and cation-exchange interactions. Compared with the monolith without the incorporation of GO, the solution and efficiency in the poly (GO-co-AAPBA-co-PETA) monolithic column were much higher and better. Besides, the ratio of ACN in the mobile phase, the concentratin of PBS and the applied voltage were also be evaluated. In addition, the GO-based monolithic column was successfully applied to separate alkylbenzenes, phenols, and peptides, respectively.