Fluorinated imidazolium ionic liquid and carbon dots co-doped silica stationary phase for efficient separation of polar compounds.

Multifunctional stationary phases are highly desirable for high-performance liquid chromatographic separations. Stationary phases functionalized with fluorine (F), ionic liquids (ILs), and carbon dots (CDs) have exhibited remarkable separation performance toward highly polar analytes. Herein, a silica stationary phase co-modified with fluorinated ILs and CDs (denoted F-ILs-CDs-SiO2) was synthesized, comprehensively characterized, and systematically evaluated for polar analytes separation. This composite material integrates the superior selectivity of fluorinated ILs, versatile intermolecular interactions endowed by CDs, and fast mass transfer kinetics inherent to silica microspheres, enabling efficient separation of polar compounds. The chromatographic retention performance of the F-ILs-CDs-SiO2 packed column was benchmarked against reference columns including F-ILs-SiO2, commercial amino-bonded silica, diol-bonded silica, C18 silica, and pentafluorophenyl (PFP) silica. The F-ILs-CDs-SiO2 column delivered outstanding resolution and high column efficiency for multiple target analytes, namely nucleosides, ginsenosides, organofluorine pesticides, and sulfonamides. A Tanaka test and mobile phase optimization experiments were subsequently performed, verifying that F-ILs-CDs-SiO2 operates via a mixed-mode retention mechanism combining reversed-phase liquid chromatography (RPLC) and hydrophilic interaction liquid chromatography (HILIC). The as-prepared F-ILs-CDs-SiO2 column possesses acceptable run-to-run repeatability, long-term stability, and batch-to-batch reproducibility. Then, the F-ILs-CDs-SiO2 column was successfully applied to the separation and quantitative analysis of ginsenoside Rg1 in rat plasma, demonstrating promising practical applicability. Collectively, the experimental results confirm that the synergistic F-ILs-CDs composite modification substantially enhances the overall separation capacity of silica substrates. This straightforward fabrication strategy and systematic performance assessment of the F-ILs-CDs-SiO2 stationary phase offer a promising avenue for the combined utilization of fluorinated ILs and CDs as advanced chromatographic separation media.