Synthesis of ionic liquid-bonded organic-silica hybrid monolithic column for capillary electrochromatography

An ionic liquid (IL) was introduced into the organic-silica hybrid monolithic column as the stationary phase for capillary electrochromatography (CEC). The monolithic silica matrix containing chloropropyl functional group was prepared by the in situ co-condensation of tetramethoxysilane and (3-chloropropyl)-trimethoxysilane via a sol-gel process and chemical modification with N-methylimidazole. The electroosmotic flow of the IL-modified hybrid monolithic column was reversed at acidic pH and the morphology of the column was characterized by scanning electron microscope. Four aromatic hydrocarbons were completely separated with 40% acetonitrile phosphate buffer as the mobile phase and seven inorganic ions were efficiently separated with the phosphate buffer on the column in CEC. Reproducibilities of migration time for four aromatic hydrocarbons (benzene, naphthalene, anthracene, chrysene) were acceptable on IL-modified hybrid monolithic columns. Relative standard deviations of run-to-run (n = 5), peak area-to-peak area (n = 5), day-to-day (n = 3) and column-to-column (n = 3) were in the range of 0.72-0.88, 1.47-5.40, 2.44-4.99 and 3.01-8.11%, respectively.