Synthesis of magnetic covalent organic framework composites for effective extraction of benzimidazole fungicides from food samples

Benzimidazoles (BZDs) are widely applied and easily accumulated through the food chain and endanger human health. Effective sample pre-treatment technology is the key procedure for trace BZDs analysis. Herein, magnetic covalent organic frameworks (Fe3O4@TRITER) nanospheres, as magnetic solid-phase extraction (MSPE) adsorbent, were synthesized and well characterized. The efficient extraction of BZDs residues depended on large specific surface of COFs and pi-pi and hydrophobic interactions between TRITER shell and BZDs. Under the optimal MSPE conditions, the developed MSPE-HPLC based on Fe3O4@TRITER method for BZDs residues afforded good linearities (0.01-1 mu g mL-1) with R2 (>= 0.996) and low limit of detections (3 ng mL-1). The developed Fe3O4@TRITER based MSPE-HPLC method was evaluated and successfully applied to determine BZDs residues in orange juice, mixed juice drink and cucumber with satisfactory recoveries (76.9-117 %) and relative standard deviations (0.10-7.90 %).