In situ growth of Zr-based metal-organic framework UiO-66-NH for open-tubular capillary electrochromatography.

The high stability and other properties of Zr(IV)-based metal organic frameworks(MOFs) make it a promising choice for chromatographic separation, while the application in open-tubular capillary electrochromatography (OT-CEC) separation has not been explored yet. Herein, we report the first example of the in-situ growth of UiO-66-NH onto the capillary for open-tubular capillary electrochromatography. UiO-66-NH consists of ZrCl and 2-amino-1,4-benzenedicarboxylic acid, which is highly porous and stable in a variety of solvents. The prepared UiO-66-NH modified capillary was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectra (FT-IR), and the results confirmed the successful growth of the UiO-66-NH . The baseline separation of chlorobenzenes, phenoxyacids and two groups of phenols was achieved owing to the combined interaction of π-π interaction, hydrophobic interaction, molecular sieve effect, electrophoretic migration and hydrogen-bonding interaction etc. Besides, the prepared capillaries showed good reproducibility, with relative standard deviations (RSDs) for intra-day, inter-day and column-to-column runs in the range of 1.38-2.60%, 3.39-4.05%, and 3.47-5.03%, respectively. Our work indicates Zr(IV)-based MOFs are promising materials as stationary phase in CEC separation.