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

Highlights: • Fe₃O₄@[NH₂]-COFs were synthesized firstly at room temperature. • Fe₃O₄@[NH₂]-COFs exhibited excellent enrichment performance towards PFAAs. • Enrichment for PFAAs was enhanced by the introduce of amino group. • Fe₃O₄@[NH₂]-COFs were used for the enrichment and analysis of PFAAs in real 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.