Carboxyl/boronic acid dual-functionalized three-component covalent organic polymer for selective enrichment of catecholamines at neutral pH

Selective separation and enrichment of human urinary catecholamines (CAs) at neutral pH are crucial for biomedical and clinical diagnostics. Herein, a novel carboxyl/boronic acid dual-functionalized three-component covalent organic polymer (COP), designated as TpBD-COOH 0.25 [B(OH) 2 ] 0.75 , was rationally designed via the combination of a multivariate synthetic strategy and post-synthetic modification. The adsorption behaviors of COPs with different functional group ratios were investigated using static adsorption and selectivity experiments. The results demonstrate that TpBD-COOH 0.25 [B(OH) 2 ] 0.75 can selectively extract CAs under neutral pH via synergistic interactions, including boronate affinity and electrostatic interactions at neutral pH. The adsorbent exhibits rapid adsorption kinetics, reaching adsorption equilibrium within 10 min, and demonstrates high adsorption capacity. The latter is determined to be 476.2 μmol dopamine/g of the adsorbent. Furthermore, TpBD-COOH 0.25 [B(OH) 2 ] 0.75 was successfully recycled five times without a notable decline in its adsorption capacity, highlighting its excellent reusability. The feasibility of this approach for practical use was validated by selectively enriching low-concentration cis-diol-containing compounds (cis-diols) from human urine samples under neutral pH conditions. Therefore, this method shows promise for broader applications in the analysis of other cis-diols.