Ionic-Liquid-Modified, Hybrid Silica Monolithic Column for Capillary Electrochromatography

An ionic liquid, 1-allyl-3-methyl imidazole chloride (AMIMCl), was synthesized to modify a terminal-vinyl organic-inorganic hybrid silica monolithic column by free-radical polymerization procedure using 2,2′-azodiisobutyronitrile (AIBN) as an initiator. Nucleotide monophosphates, phenols and benzoic acid compounds were successfully separated on this column under acidic conditions. The electroosmotic flow (EOF) was in the direction opposite to electrophoretic migration, and separation selectivity was apparently improved compared with an unmodified monolithic column, which can be attributed to the hydrophobic interactions on amyl chain, hydrogen bonding interactions on imidazole ring and electrostatic interactions. Repeatabilities of migration times for benzoic acid compounds were reasonable with RSD less than 4.0% for five consecutive within-column runs and 9.0%–9.8% for column-to-column measurements of three columns.