Magnetic covalent organic framework for effective solid-phase extraction and HPLC determination of ochratoxin A in food

Ochratoxin A (OTA) exposure in food poses great threat to human health. Magnetic solid phase extraction (MSPE) is an effective sample pre-treatment method based on liquid chromatographic analysis to monitor OTA in food. Herein, magnetic covalent organic frameworks (Fe3O4@COFs) nanospheres were prepared and well characterized. The efficient and selective extraction of OTA relied on large specific surface and inherent porosity of COFs and the hydrogen bonding, Ic-Ic and hydrophobic interactions between COF shell and OTA. The MSPE parameters were investigated in detail. Under the optimal MSPE conditions, the developed Fe3O4@DhaTabbased-MSPE-HPLC-FLD method for OTA displayed good linearity (0.1-800 mu g L-1) with R2 (0.996) and low limit of detection (0.03 mu g L-1). The proposed method was applied to determine OTA in beer, Chinese Baijiu and vinegar with satisfactory recoveries (72-111%) and relative standard deviations (0.2 to 5.5%).