Zeolite silica nanoparticles-supported open-tubular columns for isomer and chiral separation using capillary electrochromatography coupled with amperometric detection†
Novel open-tubular (OT) columns were prepared for the first time based on zeolite silica nanoparticles (SiO2NPs) as the nano coating materials. The main immobilization factors, including the size and concentration of zeolite SiO2NPs, the content of bovine serum albumin (BSA), heat temperature and time, were investigated to obtain OT columns with good stability and repeatability. Then, the separation performance of the prepared OT columns with/without BSA modifier was explored using capillary electrochromatography with an amperometric detection system. Under the optimum conditions, eight groups of model molecules, including homologues, structural isomers, epimers and enantiomers, underwent baseline separation in the prepared OT columns. The zeolite SiO2NPs-OT columns provided an efficiency of up to 108 200 plates m−1 for 4-chloro-2-methylaniline, and the OT column modified with BSA accomplished the separation and analysis of ephedrine and pseudoephedrine in ephedra herbs. The relative standard deviations of the migration time, peak area and resolution of the selected model analytes were within 8.4% for run-to-run, day-to-day, and column-to-column repeatability. Furthermore, the prepared OT columns could provide acceptable separation performance in a simple running buffer without any organic additives or surfactants, indicating their promising potential for isomer separation.