Highly selective and sensitive detection of PFASs in environmental waters via novel magnetic covalent organic frameworks

The sensitive and selective detection of per - and polyfluoroalkyl substances (PFASs) is critically important due to associated ecological and health risks. In this work, we developed a novel magnetic covalent organic framework (COF), Fe 3 O 4 @TP-3F, via an in situ Schiff base reaction. This innovative material features a core-shell structure with high surface area, uniform porosity, and robust magnetic responsiveness, enabling efficient PFASs extraction from aqueous samples. Coupling this advanced adsorbent with magnetic solid-phase extraction (MSPE) and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), we developed a sensitive analytical platform (MSPE-HPLC-MS/MS) for PFASs monitoring. The method exhibits excellent linearity over a broad concentration range (1–800 ng/L), with ultralow limits of detection (0.23–1.2 ng/L), ensuring trace-level quantification in complex environmental matrices. Application of the method to real water samples from two lakes demonstrated high accuracy and practical utility. Notably, multiple PFASs, including PFOA, PFOS, PFNA, PFDA, and PFUnDA, were identified in Tangxun Lake. Furthermore, density functional theory (DFT) calculations revealed the adsorption mechanism involves hydrogen bonding and fluorine‑fluorine interactions with the COF framework. This work established a novel COF-based magnetic adsorbent and reliable analytical method for the effective detection of PFASs, offering a powerful tool for environmental monitoring and risk assessment