Synthesis of mmixed-mode monoilithic colum for high efficiency capillary electrochrommatographic (CEC) separation

Abstract

The project was conducted with the aim of synthesizing high performance materials for the micro separation chemistry. The monolithic silica columns having mixed mode i.e., hydrophobic (C18) and anion exchange interactions was successfully synthesized by on-column modification of the hybrid TEOS/TMOS using ODS/DEA and ion exchange monomer (DMAPAA-Q) for the surface modification. The preparation of monolithic silica columns was carried out in capillaries of various sizes, 50-100 μm internal diameter. Polymerization of ODS/DEA and DMAPAA-Q monomer in a MAS-modified hybrid monolithic silica capillary column afforded a RP/SAX columns that exhibited good performance for some ions, with large number of theoretical plates or small plate height, although tailing was observed with late-eluting anions. The modified silica monolith columns achieved efficiencies of up to 170,000 theoretical plates in CEC. The results suggest that modifying a monolithic silica capillary column through the in-situ polymerization of a monomer carrying a functional group can yield high efficiency columns for ion-exchange-mode separations as well as for reversed-phase separations. CEC gave higher efficiency and faster separations compared to μLC. The synthesis of porous monolithic silica columns for CEC yields higher performance than CZE analysis. The findings will contribute to the advancement of scientific knowledge in the area of separation science. Better understanding of the fundamental interaction between the chemical compounds studied with the synthesized stationary phase inside a CEC column provide data which are to be shared through publication in journals. Keywords: Silica monolithic capillary, mixed mode, reversed phase, anion exchange, inorganic ions, capillary electrochromatography.