TpBD/UiO-66-NH2 micro–mesoporous hybrid material as a stationary phase for open tubular capillary electrochromatography

Abstract

The excellent stability of covalent organic frameworks (COFs) and the diversity of metal organic frameworks (MOFs) make MOF/COF hybrid materials promising candidates for chromatographic stationary phases. In this paper, a TpBD/UiO-66-NH₂ hybrid material was synthesized through a Schiff-base reaction between TpBD COFs and UiO-66-NH₂ MOFs; characterized using Fourier-transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy; and bonded to a capillary to prepare a TpBD/UiO-66-NH₂-bonded open tubular capillary electrochromatography (OT-CEC) column. Results suggested that the hybrid material had the crystal morphology of a single COF and MOF, a micro–mesoporous structure, and good thermal stability. The inner surface of the OT-CEC column was tightly and uniformly distributed with the stationary phase (∼1.5 μm). The baseline separation of 13 amino acids and three families (4 acidic antibiotics, 4 preservatives and 6 sulfonamides) of emerging pollutant mixtures was achieved due to the synergistic effect of TpBD and UiO-66-NH₂ in the stationary phase. The OT-CEC column showed good reproducibility and stability with relative standard deviations of migration time and resolutions in the range of 1.17–3.93% and 1.79–4.31%, respectively.