β‐Cyclodextrin Functionalized Covalent Organic Polymer Monolithic Column for Highly Selective Capillary Electrochromatographic Separation

The synthesis of covalent organic polymers (COPs) with abundant active sites remains challenging. To address this, we developed β-cyclodextrin (β-CD) functionalized COPs through a modular synthesis strategy, which was comprehensively characterized and subsequently employed as a stationary phase for capillary electrochromatographic separations. Compared with the unmodified column, the β-CD-functionalized COP monolithic column exhibited better separation performance for analytes spanning a wide range of physicochemical properties, including monosubstituted benzenes, alkylbenzenes, phenols, isomers, and chiral compounds, achieving baseline resolution > 1.5 for all tested compounds and a maximum column efficiency of 35 013 plates m^-1 for chlorobenzene. Experiments and non-covalent interaction analysis indicated that the synergistic effect between the β-CD cavity and aromatic groups enables the β-CD-functionalized COP stationary phase to exhibit multiple interaction modes (e.g., hydrophobic, π …π stacking, and hydrogen bonding), providing a theoretical foundation for the experimental data. Moreover, the column demonstrated good repeatability and stability, with relative standard deviations for intra-day, inter-day, and column-to-column repeatability all below 2.1%. The column was successfully applied to the determination of monosubstituted benzenes in wastewater samples, showing satisfactory linearity (R² ≥ 0.998), which confirms its potential for complex sample analysis.