Molded Rigid Polymer Monoliths as Separation Media for Capillary Electrochromatography

Rigid, monolithic capillary columns for reversed-phase electrochromatography have been prepared within the confines of untreated fused-silica capillaries in a single step by a simple copolymerization of ethylene dimethacrylate, butyl methacrylate, and 2-acrylamido-2-methyl-1-propanesulfonic acid in the presence of a porogenic solvent. The composition of the specifically designed ternary porogenic solvent allows fine control of the porous properties of the monolithic material over a broad range. While the electroosmotic flow through these capillary columns increases with both increasing pore size of the monolith and content of charged functionalities, better chromatographic properties have been observed for monoliths with larger surface area and hydrophobicity. Using this technique, monolithic capillary columns with an efficiency higher than 120000 plates/m have been easily obtained.