A novel C18 reversed phase organic–silica hybrid cationic monolithic capillary column with an ionic liquid as an organic monomer via a “one-pot” approach for capillary electrochromatography

Abstract

A novel C18 reversed phase (RP) organic–silica hybrid cationic monolithic capillary column with an ionic liquid (IL) as organic monomer has been fabricated by a “one-pot” approach for capillary electrochromatography (CEC). Through copolymerization, the IL, 1-vinyl-3-octadecylimidazolium bromide (VC₁₈HIm⁺Br⁻), was successfully anchored into the monolithic matrix which was formed through polycondensation of tetraethyl orthosilicate (TEOS) and triethoxyvinylsilane (VTES). Several experimental variables, which were essential to the preparation of the columns, such as the TEOS/VTES ratio, the content of H₂O and the supermolecule template, the amount of IL and the polycondensation temperature were studied in detail, and three control columns were prepared to compare with this prepared novel hybrid monolithic column. Separation of various neutral, charged and basic analytes as well as protein samples on the VC₁₈HIm⁺Br⁻ hybrid monolithic column and control columns was achieved by CEC. It was found that the prepared hybrid monolithic column possessed its own superiority in separation. Besides, the retention mechanism of neutral analytes on this column was a typical reversed phase chromatographic retention mechanism, and the separation of charged compounds depended on the combination of electrophoretic mobility, ionic exchange interaction and hydrophobic interaction. Moreover, the prepared hybrid monolithic column also settled the problem of peak tailing for separating the basic analytes, and the separation of egg white demonstrated its potential in proteome analysis.