Mixed-mode liquid chromatography with a stationary phase co-functionalized with ionic liquid embedded C18 and an aryl sulfonate group

A novel silica stationary phase was designed and prepared through thiol-ene click chemistry by functionalizing imidazolium based ionic liquid embedded C18 and an aryl sulfonate group for the mixed-mode liquid chromatography. The developed stationary phase was characterized by elemental analysis (EA), Fourier transform infrared spectrometry (FT-IR) and thermogravimetric analysis (TGA). The chromatographic performances of the prepared column were investigated by reversed phase chromatography using alkylbenzenes and positional isomers, hydrophilic interaction chromatography using nucleosides, nucleic bases and flavonoids, and ion exchange chromatography using acidic and basic analytes. The stationary phase showed faster separation and better performance for these compounds compared to the conventional alkyl stationary phase, especially for the separation of positional isomers. The investigations about water percentage and pH of the mobile phase for retentions provided information that the stationary phase offered multiple interactions with samples including hydrophobic, hydrophilic and electrostatic interactions. Moreover, improved separation efficiency of Qinghuozhimai tablet and vitamin B2 tablet were successfully achieved respectively on a single mixed-mode column. In conclusion, the multimodal retention capabilities of the developed stationary phase could offer flexible selectivity toward various types of compounds and complex samples.