Europium metal-organic frameworks/hydrogen-bonded organic frameworks as advanced stationary phase for sulfonamides analysis in open-tubular capillary electrochromatography.

Herein, europium metal-organic frameworks/hydrogen-bonded organic frameworks (Eu-MOF/HOF) was synthesized via a solvothermal method, and a chemically bonded Eu-MOF/HOF-coated capillary column was fabricated. An open-tubular capillary electrochromatography (OT-CEC) method based on Eu-MOF/HOF was developed. Characterization data demonstrated the effective formation of Eu-MOF/HOF and its firm bonding to the capillary interior surface. The effects of buffer concentration, pH, organic additive content, and applied voltage on the OT-CEC separation performance were systematically investigated using sulfonamides as the target analytes. The results demonstrated that the Eu-MOF/HOF-coated capillary column achieved good separation efficiency (resolution > 1.5) with good repeatability. The precision of the retention times was observed to be within the following ranges: intraday (0.03 %-0.04 %), interday (0.03 %-0.06 %), intercolumn (0.06 %-0.37 %), and interbatch (0.10 %-0.29 %). Similarly, the precision of the range of the peak areas were as follows: intraday (0.08 %-0.12 %), interday (0.15 %-0.18 %), intercolumn (0.37 %-0.50 %), and interbatch (0.20 %-0.30 %). Notably, the chromatographic profile remained stable after 100 consecutive runs, indicating the long-term durability of the column. Furthermore, the separation mechanism relying on hydrogen-bonding interactions was elucidated by separating structurally analogous compounds with varying numbers of hydrogen-bonding sites. The Eu-MOF/HOF-coated capillary column demonstrated good separation performance, making it a potential candidate for chromatographic applications.