Development of a carbon quantum dot-based mixed-mode stationary phase and its application in reversed-phase/hydrophilic interaction chromatography.

The development of mixed-mode chromatography (MMC) is a research hotspot in the field of separation science, and carbon quantum dots (CQDs) show remarkable potential in the development of stationary phases for chromatographic columns due to their excellent properties. In this study, amphiphilic CQDs with both hydrophilic groups and hydrophobic long-chain alkyl groups were synthesized from mercaptopropionic acid and 1,12-diaminododecane, and bonded with silica gel to obtain the column stationary phase Sil-CQDs. The stationary phase effectively separated hydrophobic and hydrophilic compounds such as alkylbenzenes, polycyclic aromatic hydrocarbons (PAHs), anilines, nucleoside bases, sulfonamides, and thioureas in both reversed-phase liquid chromatography (RPLC) and hydrophilic interaction chromatography (HILIC) modes. The impacts of chromatographic conditions on the retention behaviour of analytes were investigated. Additionally, the Sil-CQDs column showed good separation results in comparison with the Sil-Cl column without CQDs. It also exhibited outstanding stability and reproducibility, satisfying the needs for practical analysis. This work offers a novel approach for the separation and analysis of complicated materials as well as an innovative idea for the use of CQDs in mixed-mode chromatography.