Rapid, low temperature synthesis of molecularly imprinted covalent organic frameworks for the highly selective extraction of cyano pyrethroids from plant samples

Highlights: • New molecularly imprinted covalent organic frameworks (MICOFs) are synthesized. • The prepared MICOFs exhibit specific recognition toward cyano pyrethroids. • The advantages are confirmed by the quantitative analysis of cyano pyrethroids in different plant samples. - Abstract: New imine-linked molecularly imprinted covalent organic frameworks (MICOFs) were successfully prepared, using fenvalerate as the dummy template. Schiff base reaction between 1,3,5-tris(4-aminophenyl)benzene and 1,3,5-triformylphloroglucinol was rapidly achieved at room temperature, using Sc(OTf)₃ as the catalyst. The surface groups and morphologies of MICOFs were assessed by Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller surface area analysis, and scanning electron microscopy. The MICOFs exhibited high selectivity toward four structurally similar cyano pyrethroids, including fenvalerate, flucythrinate, β-cyfluthrin and λ-cyhalothrin. A method based on solid phase extraction using MICOFs coupled to high performance liquid chromatography was established for the determination of cyano pyrethroids in plant samples. Linearity in the range 0.1–200 ng g⁻¹, with correlation coefficients of 0.9981–0.9993, was obtained for the four cyano pyrethroids. Detection limits and quantification limits were in the range 0.011–0.018 ng g⁻¹ and 0.036–0.060 ng g⁻¹, respectively. Recoveries at three spiked levels ranged from 94.3% to 102.7%. The developed method is thus a promising technique for the selective extraction of cyano pyrethroids from complex matrices.