Novel Magnetic Covalent Organic Frameworks Fabricated Through In Situ Synthesis and Assembly for the Efficient Extraction and Enrichment of Six Amide Herbicides

Magnetic covalent organic frameworks (MCOFs) offer efficient adsorption via designable pore channels and active sites, along with rapid magnetic separation due to their intrinsic superparamagnetism. However, physical mixing or non-covalent assembly often leads to weak binding, causing the leaching or detachment of magnetic components during use, and compromises the well-defined crystallinity of the COF. In this study, we employed an in situ synthesis strategy at room temperature based on amidation and Schiff base reactions to fabricate a magnetic TAPT-DHTA-COF with good crystallinity and superparamagnetism. This material was used as a magnetic solid-phase extraction (MSPE) adsorbent to establish an MSPE-GC-MS/MS method for the determination of amide herbicides (AHs). The TAPT-DHTA-COF is rich in hydroxyl groups, which form strong hydrogen bonds with the polar AH molecules. In a green tea matrix, six AHs showed good linearity within the concentration range of 1–500 ng g−1, with correlation coefficients ranging from 0.9910 to 0.9982. The limits of detection were between 0.25 and 0.73 ng g−1, spiked recoveries ranged from 80.1% to 94.8%, and relative standard deviations were below 6.2%. This work offers an improved synthesis strategy for novel magnetic COFs and insights into their application in adsorbing polar pesticides.