Carbon nanostructures incorporated on methacrylate monoliths for separation of small molecules by nano-liquid chromatography

Carbon nanostructures have been incorporated to polymethacrylate monoliths to develop novel stationary phases with enhanced separation performance in nano-liquid chromatography (nano-LC). Two incorporation approaches of these nanomaterials in monoliths were investigated. Single-walled carbon nanohorns (SWNHs) were first incorporated to the polymerization mixture, followed by UV initiation. The resulting stationary phases with embedded SWNHs led to an increase in the separation performance of analytes compared to the parent monolith. Alternatively, a two-step photo-grafting approach was also adopted to attach the carbon nanoparticles onto the polymer monolith surface. The effect of the amount of SWNHs and irradiation time on the performance of the resulting composites was investigated. Moreover, these novel stationary phases were characterized by scanning electron microscopy. The photografted modified with SWNHs led to an enhanced separation performance (up to 6000 plates m−1) for test analytes. Besides, stationary phases containing oxidized SWNHs and multi-walled carbon nanotubes (MWCNTs) grafted on polymeric monoliths were prepared and a comparison in terms of separation performance was accomplished. The photografted columns with SWNHs also showed satisfactory reproducibility in terms of retention time and efficiency (RSD values below 8.6 and 1.4%, respectively).