Magnetic covalent organic framework for magnetic solid-phase extraction of carbamate pesticide residues

Herein, a new kind of magnetic covalent organic frameworks (MCOFs), named MCOF-DhaTab, using 1,3,5-tris (4-aminophenyl) benzene and 2,5-dihydroxy-1,4-phenylenedialdehyde as functional monomers of COFs and Fe3O4-NH2 nanoparticles as magnetic carrier was synthesized at room temperature through Schiff base reaction. With a large specific surface area (409.5 m2/g) and rich in benzene rings and hydroxyl groups, the prepared MCOF-DhaTab exhibited high extraction efficiency (73.8 %–88.9 %) for five carbamate pesticides (CPs). Based on it, a new method of magnetic solid phase extraction (MSPE) with MCOF-DhaTab as the sorbents coupling to high performance liquid chromatography (HPLC) − ultraviolet visible (UV) detection was developed for trace analysis of Carbaryl (CAR), Fenobucarb (FEN), Isoprocarb (ISO), Diuron (DIU), Mercaptodimethur (MER). The developed method had the advantages of low limits of detection (0.1–200 μg/L for CAR, 0.2–100 μg/L for ISO, 0.2–200 μg/L for DIU, and 0.5–200 μg/L for FEN and MER), high sensitivity, simplicity and rapidity. It was successfully used for the analysis of trace CPs in tomato, cucumber and cigar samples, showing a great application potential in pesticide residues analysis in agricultural samples.