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

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 aminefunctionalized 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-memberring 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 chromatographytandem 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.

Automated summary

A novel COF-NH2 was prepared for efficient extraction of PFAS from complex media, showing higher affinity towards PFAS. The adsorption mechanism between COF-NH2 and PFAS was tentatively revealed by density functional theory, and it demonstrated excellent performance in extracting PFAS from fish bodies.