Fabrication And Characterization Of Novel Matrices For Chromatography

The heart of a chromatographic separation process is the chromatographic media, and the key step to improve the separation technique is the development of chromatographic media. Therefore, the thesis focuses on the fabrication and characterization of novel media for chromatography.The details in this work are summarized as follows:A novel macroporous poly(glycidyl methacrylate-ethylene glycol dimethacrylate) monolith (MLS) was synthesized by in situ polymerization with customized solid granules of Na2SO4 and liquid solvent as co-porogen. After functionalized with diethylamine, an anion-exchanger monolith was obtained. Compared with the conventional monolith (ML) using organic solvents only as a porogen, the improved monolith (MLS) showed higher column efficiency and column permeability without obviously decreasing the dynamic binding capacity of protein. It is considered that the superpores introduced by the solid granules play an important role for the improvement of the monolith performance.To enhance the binding capacity of protein to the adsorbent, poly(glycidyl methacrylate-diethylamine) tentacles were grafted onto the pore surface of the macroporous monolith using ceric ammonium nitrate as a imitator. This further increased the dynamic binding capacity of BSA to 74.7 mg/ml, about three times higher than that of the monolith without the grafted tentacles. The grafted chains on the pore surface would hinder protein mass transfer, leading to the decrease of column efficiency. Despite this unfavorable effect, the grafted monolith still exhibited high permeability.Porous titania beads were synthesized by a sol-gel-templating method using agarose gel as template. The dipping time and repeated mineralization cycle played the important roles in the diffusion of the titanium precursors into templates and the maintenance of porous structure of the resultant titania beads. Calcination temperature affected the size and phase state of titania nanocrystals, specific surface area, pore volume and porosity. By control of these factors, it was possible to fabricate porous titania beads of 7 to 150μm in mean diameter. Larger-sized titania beads could be easily produced by using larger-sized agarose gel. Finally, flow hydrodynamics, column efficiency and separation performance were studied using the column packed with the optimized titania beads of 15μm. The results indicate that the porous titania beads had excellent mechanical stability, and the column exhibited high column efficiency and good separation performance of three aniline derivatives. Compared with other approaches to the fabrication of titania beads, the present strategy provides a readily controllable procedure for the preparation of well-defined beads of various sizes determined by the initial templates, so it may open a new way to the fabrication of well-defined inorganic beads with tailored properties for HPLC packings.Macroporous calcium titanate beads were fabricated through sol-gel mineralization of agarose gel entrapping calcium carbonate and subsequent heating treatment. In the reaction process, calcium carbonate was applied not only as porogen, but also as calcium source in the synthesis of calcium titanate material. The pore size distribution, porosity, specific surface area of final materials can be controlled by the temperature and content of calcium carbonate granules in the agarose gel. Finally, the optimized macroporous calcium titanate beads were investigated as chromatographic media. It exhibited good separation property and showed less nonspecific adsorption of basic compounds compared with titania beads.