A novel ionic liquid monolithic column and its separation properties in capillary electrochromatography

Area of Science:

• Analytical Chemistry
• Separation Science
• Materials Science

Background:

• Capillary electrochromatography (CEC) utilizes monolithic columns for efficient separations.
• Developing monolithic columns with stable electroosmotic flow and reduced analyte adsorption is crucial.

Purpose of the Study:

• To prepare a novel ionic liquid (IL) monolithic capillary column using copolymerization.
• To optimize the column preparation for enhanced performance in CEC.

Main Methods:

• Thermal free radical copolymerization of 1-vinyl-3-octylimidazolium chloride (ViOcIm(+)Cl(-)) with lauryl methacrylate (LMA) and ethylene dimethacrylate (EDMA).
• Optimization of monomer, porogen, and cross-linker ratios.
• Characterization using scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR).
• Performance evaluation through separation of alkylbenzenes, thiourea, and amino acids.

Main Results:

• The IL-monolithic column exhibited stable reversed electroosmotic flow (EOF) from pH 2.0 to 12.0.
• Effective elimination of wall adsorption for basic analytes was achieved.
• Good pore properties, mechanical stability, and permeability were confirmed.
• High column efficiency was demonstrated, with a lowest plate height of ~6.8 μm for thiourea (~147,000 plates m(-1)).

Conclusions:

• Ionic liquids are promising functional monomers for fabricating organic polymer-based monolithic columns in CEC.
• The developed IL-monolithic column offers superior performance for complex separations.