Sulfonic acid-functionalized covalent organic framework-based dispersive solid-phase extraction combined with miniaturized mass spectrometry for the analysis of diquat in biological samples.

Diquat (DQ), a rapid-acting and nonselective herbicide, can directly contaminate the environment and harm human health during its application or production processes. Early accurate detection is essential for timely clinical intervention. Herein, a novel analytical method that integrates dispersive solid-phase extraction (dSPE) with miniaturized mass spectrometry (mini-MS) for the detection of DQ was established. A sulfonic acid-functionalized covalent organic framework (COF-SF) was synthesized via a facile interfacial synthesis strategy and thoroughly characterized. The as-prepared COF-SF served as an efficient adsorbent for the rapid extraction of DQ from biological fluids, achieving a high adsorption capacity of 92.89 mg/g within 4 min. The potential adsorption mechanism, which may be attributed to synergistic interactions, was preliminarily explored. The developed COF-SF-based dSPE-mini-MS method demonstrated a wide linear range with correlation coefficients (R2) greater than 0.9975, low detection limits (6.73-9.81 μg/L), satisfactory recoveries (77.70-83.71%), and good repeatability (RSD ≤ 5.39%). Due to the limited clinical samples obtained for validating this method, further research with more samples is needed to confirm its practicality. Nevertheless, this work offers a potential method for toxicant detection in complex biological matrices, which may contribute to rapid poisoning screening.