Preparation of stir bars coated with N-modified COFs and application to estrogen detection in dairy products

This study synthesized three covalent organic frameworks (COFs): TAPB-TA-COF, TAPP-TA-COF, and TAPT-TA-COF, with increasing N atom content, under low-energy consumption conditions at room temperature. These COFs were applied in stir bar sorptive extraction (SBSE) of estrogens. TAPT-TA-COF, possessing the highest N-atom density, exhibited superior extraction efficiency due to enhanced π-π interactions and hydrogen bonding with estrogen molecules. Under optimized conditions, TAPT-TA-COF-coated stir bars achieved linear ranges of 1-800 μg/L, detection limits of 0.06-0.15 μg/L (S/N = 3), and enrichment factors of 42.3 for hexoestrolum (The theoretical enrichment factor is 50 times). The optimized TAPT-TA-COF-SBSE-HPLC-DAD method successfully analyzed estrogens in dairy products. This study highlights the relationship between the number of N-atoms in COFs and their efficiency in adsorbing estrogens, providing valuable guidance for the strategic design of functional materials.