A covalent organic framework with hydrazone bond for efficient enrichment of phenolic pollutants.

To address the challenges of phenolic pollutants (PPs), including high toxicity, poor degradability, and difficulty in trace enrichment, this work developed a hydrazone-linked covalent organic framework (DTB-COF). DTB-COF features abundant NH hydrogen bond donors and CN hydrogen bond acceptors within its pores, enabling synergistic adsorption of PPs through hydrogen bonding, hydrophobic interactions, π-π stacking, and pore filling. Employing DTB-COF as a solid-phase extraction adsorbent combined with high-performance liquid chromatography, we established a quantitative detection method. In juice, milk, and honey, the limits of detection were 0.12-0.22, 0.29-0.58, and 0.53-1.51 ng mL-1, respectively; the spiked recoveries ranged from 87.0%-112.0%, 89.1%-112.9%, and 87.6%-112.9%, respectively, with relative standard deviations below 6.89%. This method demonstrates high accuracy and good reproducibility, effectively addressing the limitations of traditional adsorbents, such as low capacity and poor reproducibility, offers a reliable and efficient strategy for the trace analysis of PPs in food matrices.