Preparation and evaluation of o-phenanthroline immobilized on a hybrid silica monolith modified with ionic liquids for reversed-phase pressurized capillary electrochromatography

A novel o -phenanthroline-immobilized ionic-liquid-modified hybrid monolith for capillary electrochromatography was synthesized based on chloropropyl-silica, which was prepared by the in situ polymerization of tetramethoxysilane and 3-chloropropyltrimethoxysilane via a sol–gel process. The morphology of the hybrid monolith was characterized by scanning electron microscopy, and relatively stable anodic electroosmotic flow was observed under a broad pH ranged from pH 3.0 to 9.0. The separation mechanism was investigated by separating four neutral molecules (toluene, dimethylformamide, formamide, and thiourea). The obtained hybrid monolith possessed an obviously reversed-phase retention mechanism, but when the acetonitrile content in the mobile phase was >90% v/v, a weak hydrophilic mechanism was observed on the resultant o -phenanthroline-modified chloropropyl-silica hybrid monolith. The reproducibility of the column was also investigated by measuring relative standard deviations of the migration time for four neutral molecules. Relative standard deviations of run to run ( n = 3), day to day ( n = 3), and column to column ( n = 3) were in the range of 0.4–0.7, 0.9–2.1, and 1.4–3.3%, respectively. Basic separations of various polar analytes including phenols and aromatic amines were successfully achieved.