Preparation And Application Of Three Hydrophilic Monolithic Columns

Monolith, as a newly developed chromatographic packing compared with traditional fillers, has many advantages, such as: low column back pressure, high column efficiency, good design, convenient way of preparation and so on. According to different separation modes, monolithic column can be divided into multiple modes, reversed phase, normal phase, hydrophobic, hydrophilic, ion exchange, the hydrophilic mode attracts more attentions by researchers as it can solve problems of the polar compounds, it is noteworthy that the current research of hydrophilic mode is not sufficient as the reports about the types and preparation methods of hydrophilic monolithic column are few, therefore, it is very necessary to prepare novel hydrophilic monoliths and develop new methods of preparation.In this paper, three different hydrophilic compounds were chosen as functional monomers, with three strategies including the approach of a sol-gel “one-pot”, radical polymerization and graft copolymerization for three hydrophilic columns respectively. Specific work is as follows:1. Taking tetramethoxysilane as skeleton monmer, mercaptopropyl trimethoxysilane as crosslinker and methacrylic acid as functional monomer, a novel sol-gel “one-pot” approach in tandem with a radical-mediated thiol-ene reaction was developed for the synthesis of a methacrylic acid-based hybrid monolith. The physical and chemical structure characterization of the resulted monolith showed that the carboxylic acid functional groups was successfully introduced in the monolithic column, and uniform pore structure and good permeability were found. Further chromatographic characterization showed that the column hydrophilicity with higher organic phase in mobile phase, and the addition of triethylamine showed the capacity of the hydrophilic separation of the column was dependent on a weak base environmental. Thus, the nucleosides and other small molecules can be baseline separated with high organic phase, and the monolith was successfully applied to the separation of protein for exploring its application in the separation of complex samples.2. With 1,4-acryloyl piperazine(PDA) as a hydrophilic monomer and POSS as crosslinker, the poly(PDA-co-POSS) monolith was synthesized. The overall effects of experimental conditions were optimized. The physical and chemical characterization of the monolith was studied and showed mechanical stability and good permeability. The chromatographyic characterization showed that the monolith possessed suitable hydrophilicity with higher organic phase in mobile phase and good separation of nucleosides, acids and other small polar molecules were achieved.3. Taking PEGDA as crosslinker for skeletons and HPC as grafted polysaccharide, the cellulose monolithic column with surface functional was synthesized via a graft copolymerization reaction. HPC can be derived without pre-situ access branch. Through the optimization of experimental conditions, the monolith with a uniform structure and moderate permeability was obtained. Characterization results showed that HPC has been successfully introduced and chromatographic characterization showed that monolithic column possessed good hydrophilicity and polar compounds were well separated. The way of preparation of monolith provides a potential for preparing a water-soluble polysaccharide materials.