Self-polymerization-driven high-purity hydrophobic carbon dots incorporated monolithic columns for high-selectivity reversed-phase capillary liquid chromatography

Carbon dots (CDs) hold great potential for chromatographic separations. However, their application in chromatographic stationary phases has been limited by two major synthetic challenges: (1) insufficient control over surface chemoselectivity caused by impurity co-adsorption, and (2) structural heterogeneity arising from uncontrolled solvothermal byproducts. To address these limitations, we developed a self-polymerization-driven strategy to synthesize high-purity hydrophobic CDs from 8-amino-2-naphthol (8N2OH) and 2,3-dihydroxynaphthalene (DHN). These CDs were incorporated into organic polymer monoliths via in situ copolymerization, yielding novel 8N2OH-CDs and DHN-CDs hybrid monolithic stationary phases for reversed-phase capillary liquid chromatography. The synthesized CDs were thoroughly characterized, with high purity confirmed by proton nuclear magnetic resonance. The resulting monolithic columns exhibited high permeability and uniformity, as demonstrated by field emission scanning electron microscopy, attributed to the excellent dispersion of the CDs. The chromatographic performance was evaluated using nine types of neutral, alkaline, and acidic compounds, as well as Tanaka standard test mixtures. Compared to unmodified columns, the CD-modified monoliths showed significantly enhanced retention strength and selectivity, supported by Tanaka tests revealing multifactorial retention mechanisms. This work demonstrates the potential of high-purity hydrophobic CDs as versatile modifiers for high-performance chromatographic stationary phases.