Effective enrichment and detection of plant growth regulators in fruits and vegetables using a novel magnetic covalent organic framework material as the adsorbents

The present research reported a facile strategy for the synthesis of a novel magnetic covalent organic frameworks (Fe₃O₄@COF(TpDA)) material and applied it as a sorbent for magnetic solid phase extraction of plant growth regulators from fruits and vegetables. The prepared Fe₃O₄@COF materials showed many attractive features involving large specific surface area (180.2 m²/g) and high saturation magnetization (62.3 emu/g), which enabled it an ideal sorbent for sample pretreatment. The experimental conditions affecting the extraction performance were optimized systematically, including eluent, amount of sorbent, adsorption time and desorption time. The extracted samples were detected by HPLC-DAD. Under the optimized conditions, the proposed method exhibited good linearity (R ≥ 0.9990) and low limits of detection (4.68–7.51 μg/L). Satisfactory recoveries were calculated to be 83.0–105.0%. Finally, the proposed method was successfully applied to determination of plant growth regulators in fruits and vegetables, indicating the potential prospect of the Fe₃O₄@COF(TpDA) materials in sample pretreatment.