Highly fluorinated magnetic covalent organic framework for efficient adsorption and sensitive detection of microcystin toxin in aqueous samples.

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 (Qmax = 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.