Eutectogel-mediated metal organic framework@silica composites: Enabling multi-mode separation in high-performance liquid chromatography.

Eutectogels, a class of emerging soft materials, have attracted considerable interest owing to their three-dimensional network architectures, inherent hydrophilicity, and tunable structural properties. Notwithstanding their advantages in environmental friendliness, cost-effectiveness and facile preparation relative to conventional gels, eutectogels encounter a pivotal challenge in chromatographic applications. The primary limitation lies in their poor stability as packing materials, arising from both the aqueous instability of their internal hydrogen bond networks and their pronounced swelling tendency in aqueous media. The present study thus introduced the hydrophobic hydrogen bond donor and acceptor to construct a hydrophobic deep eutectic solvent, aiming to mitigate the swelling of eutectogel-based stationary phase in aqueous media. Simultaneously, porous MIL-88A material was integrated to create a rigid-flexible composite, which synergistically addressed the inherent swelling issue of eutectogels. The fabricated MIL-88A/Eutectogel@SiO2 chromatographic column exhibited efficient separation of various analytes, including aromatic positional isomers, hydrophilic nucleosides/bases, and benzoic acid derivatives. Furthermore, the strategic introduction of l-lactic acid into the eutectogel enabled effective separation of chiral analytes on this chromatographic column. Systematic investigations were performed on the separation mechanisms and chromatographic parameter optimization. The practical utility of the MIL-88A/Eutectogel@SiO2 column was further demonstrated through the successful detection of polycyclic aromatic hydrocarbons and antibiotics in actual samples. This study presents a green approach for fabricating a composite chromatographic stationary phase by integrating the synergistic effects of metal organic framework and eutectogel, thereby expanding their application domains in separation science.