Sea-urchin-like covalent organic framework as solid-phase microextraction fiber coating for sensitive detection of trace pyrethroid insecticides in water.

Pyrethroid insecticides residues in water pose a critical threat to the environment from widespread production and overuse. Therefore, it is of major relevance to develop a sensitive and efficient method to detect pyrethroid insecticides in water. In this paper, a covalent organic framework (COF) with NHCO as the structural unit was synthesized using a simple condensation reaction of TTL (NH₂) and TDBA (COOH). Various characterization results and density functional theory (DFT) calculations demonstrated that multiple interactions synergistically promoted the adsorption of pyrethroid insecticides on COF_TDBA-TTL. Based on the excellent extraction capability of COF_TDBA-TTL, efficient detection of 11 pyrethroid insecticides in water was achieved using COF_TDBA-TTL-coated SPME fiber and gas chromatography-tandem mass spectrometry (GC-MS). The results showed that the extraction enhancement factors (EFs) of pyrethroid insecticides were as high as 2584-7199, and the extraction efficiencies were 3.28-446 times higher than that of commercial fiber, which reflected its high adsorption property. Meanwhile, the limits of detection (LODs) of the COF_TDBA-TTL coated fiber were as low as 0.170-1.68 ng/L under the optimal conditions, and the recoveries of 11 pyrethroid insecticides in the actual water samples were 88.5-108 %. In conclusion, the SPME-GC-MS method based on COF_TDBA-TTL coated fiber was simple, rapid, and efficient, and should have a promising application in trace detection of pyrethroid insecticides in the environment.