Room-temperature synthesis of amino-functionalized magnetic covalent organic frameworks for efficient extraction of perfluoroalkyl acids in environmental water samples.

The novel amino-functionalized magnetic covalent organic framework nanocomposites (Fe3O4@[NH2]-COFs) were fabricated at room temperature, which were explored as a magnetic adsorbent for magnetic solid-phase extraction (MSPE). On the basis of the hydrophobic surfaces of magnetic nanocomposites and introduction of primary amines into the COFs shell, Fe3O4@[NH2]-COFs displayed excellent enrichment capacity in "catching" ultratrace perfluoroalkyl acids (PFAAs) from water samples because of the synergistic combination of hydrophobic and electrostatic interactions between PFAAs and Fe3O4@[NH2]-COFs. Under the optimized pretreatment and instrumental parameters, the proposed pretreatment approach, which hybridized MSPE using Fe3O4@[NH2]-COFs and HPLC-MS/MS, displayed favorable linearity (10-10,000 ng L-1) with R2 (0.9990-0.9999), low limits of detection (0.05-0.38 ng L-1), and excellent repeatability (3.7-9.2%). Moreover, the established approach was successfully utilized to determine PFAAs in real water samples with spiked recoveries ranging from 72.1% to 115.4%. Results indicated that Fe3O4@[NH2]-COFs would be a potential alternative for MSPE of PFAAs at ultra-low levels.