Facile synthesis of magnetic bromine-functionalized covalent organic framework for efficient solid-phase...

The widespread use of polybrominated diphenyl ethers (PBDEs) as flame retardants has led to their pervasive presence in aquatic environments, posing serious health risks. Herein, we report a facile synthesis of a novel magnetic bromine-functionalized covalent organic framework (Fe₃O₄@Br-COF) for the efficient magnetic solid-phase microextraction (MSPE) of trace PBDEs from water. A one-pot solvothermal strategy was employed to fabricate Fe₃O₄@Br-COF using 1,3,5-tris(4-aminophenyl)benzene and 2,5-dibromoterephthalaldehyde as building blocks. The Br-COF coating significantly enhances the extraction selectivity and efficiency toward PBDEs through synergistic interactions, including potential halogen bonding, π-π stacking, and hydrophobic interactions. The MSPE conditions, including sorbent dosage, extraction time, pH, and desorption parameters, were systematically optimized. Under optimal conditions, the developed Fe₃O₄@Br-COF-MSPE coupled with high-performance liquid chromatography-diode array detection (HPLC-DAD) demonstrated excellent analytical sensitivity and linearity for four PBDEs (TPB, BBPE, TBBPA, and PBDE), with wide linear ranges (0.5-250 ng/mL, R² > 0.997), low limits of detection (0.005-0.01 ng/mL), and good precision (relative standard deviations < 5.7%). The method was successfully applied to the analysis of PBDEs in environmental water samples, yielding satisfactory recoveries (81.6-109.3%). Moreover, the Fe₃O₄@Br-COF adsorbent demonstrated good reusability for up to five consecutive cycles. This work highlights the great potential of bromine-functionalized magnetic COFs as a powerful platform for the selective enrichment and determination of halogenated organic pollutants in complex environmental matrices.