An amine-functionalized olefin-linked covalent organic framework used for the solid-phase microextraction of legacy and emerging per- and polyfluoroalkyl substances in fish

Abstract

Due to the environmental persistence and various health problems associated with per- and polyfluoroalkyl substances (PFASs), they have come under increased public scrutiny. However, the efficient extraction of PFASs from complex media remains challenging. Herein, an olefin-linked covalent organic framework (COF-CN) has been prepared via a Knoevenagel condensation reaction, followed by reduction using LiAlH4 to form an amine-functionalized COF (COF-NH2). The characterization results demonstrated that the crystal structure was maintained during the post-modification step. Isothermal and kinetic adsorption studies showed the higher affinity of COF-NH2 toward PFASs. Based on density functional theory, the adsorption mechanism of the stable six-member-ring structure formed between COF-NH2 and PFASs via hydrogen bonding was tentatively revealed. After optimizing the solid-phase microextraction parameters, legacy and emerging PFASs were efficiently extracted from fish using the COF-NH2 coating, followed by detection using ultra-performance liquid chromatography-tandem mass spectrometry. The method exhibited ideal linearity, low limits of quantification, excellent precision, and high relative recoveries. Finally, the bioconcentration kinetics for goldfish was studied, which can provide a feasible platform for investigating the accumulate ion and toxicity of PFASs.