Capillary electrochromatography using monoamine- and triamine-bonded silica nanoparticles as pseudostationary phases

• Capillary electrochromatography using 20–80-nm sized amine-bonded silica nanoparticles.
• Aminopropyl silica and diethylene-triamine-bonded silica was evaluated.
• Adsorption of amine bonded silica to capillary surface induces fast reversed electroosmotic flow.
• The method was applied to the separation of glucose oligomers.

Monoamine- and triamine-bonded silica nanoparticles were prepared using 3-aminopropyltrimethoxysilane and N1-(3-trimethoxysilylpropyl)diethylenetriamine, respectively, and used as pseudostationary phases for capillary electrochromatography. The amine-bonded silica nanoparticles were tightly adsorbed on the inner wall of a capillary and generated fast electro-osmotic flow (2.59 × 10−4 cm2 V−1 s−1) toward the anode in an electric field. The electro-osmotic velocities obtained with 20 nm triamine-bonded silica were three to five times larger than those generated by a fused silica capillary and two times faster than those for the commercial cationic polymer-modified capillary. Fast electro-osmotic flow enables rapid analysis. This method was applied to hydrophilic interaction chromatography (HILIC) mode separation of various samples including the size separation of glucose oligomer derivatives and the resolution of four nucleic acid bases.