Electroneutral silica-based hybrid monolith for hydrophilic interaction capillary electrochromatography

A novel electroneutral and polar silica-based hybrid monolith was developed by an in situ copolymerization of 2-hydroxyethylmethacrylate (HEMA) and polyhedral oligomeric silsesquioxane methacryl substituted (PUSS-MA), and successfully employed for hydrophilic interaction capillary electrochromatography (HI-CEC). A good mechanical stability of the prepared monolith was gained with the permeability decreasing from 6.52 x 10(-14) m(2) to 4.61 x 10(-14) m(2) when mobile phase changed from ACN to water. A significant cathodal EOF was obtained through attracting ions from the mobile phase despite the fact that it was devoid of ionizable functional groups on the surface of stationary phases, and a typical HI-CEC mechanism was achieved. The morphologies of the hybrid silica-based monolithic matrixes were observed, and the performance of this silica-based hybrid monolith was also investigated. Satisfactory column performances were carried out for both the neutral and charged analytes with HI-CEC. The analytes including uncharged amides and phenols, charged nucleic acid bases and nucleosides and enkephalins. were well separated with good peak symmetry. High separation efficiencies of charged alkaloids and enkephalins could get up to 145,000 plates/m and 75,000 plates/m, respectively. (C) 2012 Elsevier B.V. All rights reserved.