New Urea-Functionalized Magnetic Covalent Organic Framework for the Enrichment and Detection of Carbamate Pesticides in Lonicera japonica and Chrysanthemum morifolium

In this study, based on the structural features of seven carbamate pesticides, a urea-functionalized magnetic covalent organic framework materials (COFs) was synthesized using 4’,5’-bis(4-aminophenyl)-[1,1’:2’,1”-terphenyl]-4,4”-diamine (BATD) and 1,4-diisocyanatobenzene (PPDI) as monomers, and it was used as a sorbent for the magnetic solidphase extraction (MSPE) of carbamate pesticide residues. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed the successful modification of the material onto Fe₃O₄ nanoparticles. The extraction conditions were optimized, and the MSPE material was coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to establish a sensitive and accurate method for the enrichment and detection of carbamate pesticide residues in honeysuckle flower (Lonicera japonica) and chrysanthemum flower (Chrysanthemum morifolium). The analytical method demonstrated good linearity (R² > 0.9962) in the concentration range of 2–100 µg/kg, with recovery rates between 76.90% and 109.86%. The limits of detection were 0.03–0.6 µg/kg, and the limits of quantification were 0.1–2.0 µg/kg.