Graphene oxide decorated monolithic column as stationary phase for capillary electrochromatography

• Vinylization of GO by p-aminostyrene was controllable and purifiable.
• Vinylized GO was first covalently bonded with the polystyrene monolith via in-situ one-step copolymerization.
• Investigations of EOF affected by electrolyte concentration and pH, acetonitrile composition and applied voltage demonstrated a stable EOF of nonlinear electrokinetics in a wide pH range.
• Minute alteration by pH, good stability and long usage time was ascribed by the polystyrene-based material.

In this work, GO bonded monolith (pAS-GO@PS-DVB) as the stationary phase for capillary electrochromatography was fabricated, which was achieved by a simple one-step in-situ copolymerization of styrene and vinylized GO in the presence of divinylbenzene as a cross-linker. GO functionalization was primarily completed using p-aminostyrene based on condensation reaction between amino and carboxyl groups. The characterization by infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy proved the covalent bonding of GO on the monolith. The average pore diameter via Barrett–Joyner–Halenda, specific surface area and pore volume via Brunauer-Emmett-Teller equation by nitrogen adsorption/desorption were determined to be 112.4 nm, 485.8 m2 g−1 and 1.4 cm3 g−1, respectively. The pAS-GO@PS-DVB monolithic column gave effective separation for a wide range of aromatic compounds, which was based on hydrogen bonding and π-π interactions of GO with polar and/or non-polar organic compounds. The reproducibility in terms of the precisions of migration time, peak height and peak area was estimated below 6% using thiourea and other aromatic compounds. Furthermore, the differences of migration time, peak height and peak area between the first-week analysis and the forth-week analysis were less than 19%, indicating good stability of the proposed monolithic column in one month. The applicability of the pAS-GO@PS-DVB monolith was also demonstrated by baseline separation of three phenols and three anilines.