Application of graphene as the stationary phase for open-tubular capillary electrochromatography

We reported the application of graphene as a novel stationary phase in open-tubular capillary electrochromatography (OTCEC). The OT column was easily fabricated by electrostatic assembly of poly(diallydimethylammonium chloride) followed by self-adsorption of negatively charged graphene. The chromatographic properties of graphene-coated OT column were investigated by separation of nitroaniline isomers through variation of the buffer pH, sodium dodecyl sulfate concentration and separation voltage. The results demonstrate the application of graphene in OTCEC greatly improves the separation by largely enhancing the surface area thus increasing stationary/mobile phase interaction. The proposed OT column exhibits good repeatability with run-to-run RSD of retention time as low as 1.5% (n = 5), and excellent stability for at least two-week usage with total ∼200 runs. The method was successfully applied for analysis of nitroaniline isomers in hair dye samples.