Monolithic columns with incorporated titanium dioxide nanoparticles for hydrophilic interaction liquid chromatography

This research article presents the preparation and characterisation of monolithic columns with incorporated titanium dioxide nanoparticles (TDNPs) and their subsequent use in hydrophilic interaction liquid chromatography (HILIC) of small relatively polar solutes. The monolithic support was based on the in situ polymerisation of glyceryl monomethacrylate (GMM) and ethylene glycol dimethacrylate (EDMA) yielding the poly(GMM-co-EDMA) monolith for the incorporation of TDNPs. The poly(GMM-co-EDMA) functioned as a ‘true support’ for TDNPs’ ‘stationary phases’ as manifested by TDNPs being the major contributor to solute retention, column selectivity and separation efficiencies. In other words, monolithic columns with ‘TDNPs stationary phases’ were achieved with the understanding that the contribution of the monolith proper to the solute© retention was at its minimum. The TDNPs were subjected to probe tip high-power sonication at an output power of 10 W for 20 minutes with the aim of better dispersing the incorporated TDNPs into the monoliths under investigation. In fact, high-power sonication yielded columns with a relatively higher plate count (~3-fold increase) when compared to low-power sonication. Overall, the prepared TDNPs stationary phases proved useful in HILIC of small polar solutes including dimethyl formamide, formamide, thiourea, nucleobases and nucleosides.