Highly fluorinated magnetic covalent organic framework for efficient adsorption and sensitive detection of...

The effective adsorption and sensitive determination of microcystin-LR (MC-LR) are crucial for the environment and human health. In this work, a highly fluorinated magnetic covalent organic framework (denoted as Fe₃O₄@TabTfa-F₄) was synthesized through a simple strategy. The morphology and structure of the as-prepared Fe₃O₄@TabTfa-F₄ were investigated and Fe₃O₄@TabTfa-F₄ showed that it had a high specific surface area (442.3 m² g^-1), high fluorine content (6.0%), large pore volume (0.255 cm³ g^-1), and strong magnetic responses (31.0 emu g^-1). The new sorbent Fe₃O₄@TabTfa-F₄ was applied for MC-LR adsorption. The adsorption behavior was investigated, and the results followed pseudo-second-order kinetics and the Langmuir adsorption model. The excellent adsorption capacities for MC-LR (Q_max = 495.1 mg g^-1) may be due to the formation of numerous hydrogen bonds, hydrophobic interaction, and π-π stacking interaction between MC-LR and Fe₃O₄@TabTfa-F₄. Afterward, Fe₃O₄@TabTfa-F₄ was used to extract MC-LR from aqueous samples, followed by high-performance liquid chromatography incorporated with UV spectroscopy. The major parameters that influenced the extraction performance were investigated. The developed method exhibited good linearity in the range of 0.25-20 ng L^-1. Under the optimum conditions, limits of detection (S/N=3), limits of quantitation (S/N=10), enrichment factor and relative standard deviation were calculated to be 0.041 ng mL^-1, 0.13 ng mL^-1, 425, and 9.6%, respectively. The spiked recoveries ranged within 75.3%-108.6%. These findings indicate that Fe₃O₄@TabTfa-F₄ has potential application to the adsorption and sensitive detection of MC-LR from aqueous samples.