Imidazolium ionic liquids-derived carbon dots-modified silica stationary phase for hydrophilic interaction chromatography

In this study, imidazolium ionic liquids-derived carbon dots (ImCDs) were successfully synthesized and bonded on the surface of spherical porous silica as a new stationary phase (Sil-ImCDs) for hydrophilic interaction chromatography (HILIC). First, the ImCDs were synthesized by the reaction of amino ionic liquids with citric acid , and then they were grafted onto the surface of aminopropyl-modified silica. A series of characterizations including infrared spectra, elemental analysis and laser confocal microscope proved that the preparation was successful. It was found that the Sil-ImCDs had good separation efficiency in the separation of bases, nucleosides , amino acids , saccharides and ginsenosides . It is interesting that we found that Sil-ImCDs has better hydrophilic chromatographic performance compared with methylimidazole-modified silica and aminopropyl-modified silica. It may be due to the rich functional group which is available after the formation of carbon dots from imidazolium ionic liquids and citric acid.