Hybrid monolithic columns with nanoparticles incorporated for capillary electrochromatography

The core–shell silica nanoparticles Fe3O4@SiO2/NH2, wormlike and hexagonal SBA-15 silica were incorporated into polymethacrylate monolithic columns containing butyl methacrylate (BMA) and ethylene dimethacrylate (EDMA), respectively to develop novel stationary phases with mixing mechanism of reverse phase and ion exchange. Experimental conditions including types of nanoparticles, dispersion pattern, nanoparticles concentration, column placement mode, and reaction temperature were optimized for simple and stable column preparation. The poly(BMA-EDMA-Fe3O4@SiO2/NH2) and poly(BMA-EDMA-SBA-15/NH2) (both wormlike and hexagonal shape nanoparticles) monolithic columns were evaluated with mixture of organic acids as sample in capillary electrochromatography (CEC) mode and the relative column efficiency reaches 290,000 plates/m. The results indicate that the incorporation of nanoparticles with various shapes enhances both selectivity and column efficiency due to high specific surface area of nanoparticles and mixing separation mechanism. In addition, poly(BMA-EDMA-Fe3O4@SiO2/NH2) monolith capillary column was applied to separation of aqueous extract of rhizoma gastrodiae and showed great potential in the method development of complex samples.