One-stop solution for wide polar range compounds: Preparation and application of quaternary ammonium salt molecular cage stationary phase.

The separation and analysis of complex samples with wide polar range on a singular column is always a difficult problem in separation and analysis science. In this study, the RCC3-R molecular cage modified with the quaternary ammonium salt stationary phase (RCC3-GQ@silica) was successfully prepared and applicated in the separation of wide polar range compounds. In the Reverse Phase Liquid Chromatography (RPLC) mode, due to the hydrophobicity and π-π interactions provided by the cyclohexane and benzene rings in the molecular cage structure, this stationary phase demonstrated effective separation capabilities for alkylbenzenes, polycyclic aromatic hydrocarbons, phenols, and anilines. In the Hydrophilic Interaction Liquid Chromatography (HILIC) mode, the study explored the separation performance of this stationary phase for sugars and inorganic salts. Utilizing a mixed mode of HILIC/RPLC/Ion Exchange Chromatography (IEC), effective separation was achieved for sulfonamides, nucleosides, acids, and amino acids, indicating good separation effects for medium to strongly polar compounds as well as various hydrophilic compounds. Combining various separation modes, the RCC3-GQ@silica stationary phase successfully separated 91 compounds across 15 categories. These results not only demonstrate the potential of the stationary phase in expanding the range of polarities of analyzable compounds and achieving multipurpose use on a single column, but also confirm its effective separation of nucleosides in pure water systems, further emphasizing the significant application potential of RCC3-GQ@silica stationary phase in the field of green chemistry.