Cationic Ionic Liquids Organic Ligands Based Metal–Organic Frameworks for Fabrication of Core–Shell Microspheres for Hydrophilic Interaction Liquid Chromatography

In this study, new metal–organic frameworks (MOFs) nanocrystals modified SiO₂ core–shell microspheres were designed with cationic ionic liquids (ILs) 1,3-bis­(4-carboxybutyl)­imidazolium bromide (ILI) as organic ligands. By further adjustment the growth cycles, the new ILI-01@SiO₂ core–shell stationary phase was facilely fabricated. The developed stationary phase was respectively characterized via element analysis, thermogravimetric analysis, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectrometry. Because the introduction of cationic imidazolium-based ILs ILI for fabrication of the MOFs nanocrystals shell, the new stationary phase exhibits the retention mechanism of hydrophilic interaction liquid chromatography (HILIC). Many polar samples, such as amides, vitamins, nucleic acid bases, and nucleosides, were utilized to investigate the performance of the prepared ILI-01@SiO₂ column. Compared to the conventional aminosilica column, the new ILI-01@SiO₂ column displays high separation selectivity in a shorter separation time. Furthermore, the new ILI-01@SiO₂ column was also used for detection of illegal melamine addition in the baby formula. All the above results demonstrate the new ILI-01@SiO₂ core–shell stationary phase is of good potentials for high-selectivity separation the polar samples.