FeO/ZIFs-based magnetic solid-phase extraction for the effective extraction of two precursors with diverse structures in aflatoxin B biosynthetic pathway.

The aflatoxin B (AFB) early warning technique based on precursors is an effective strategy for the prevention of AFB contamination risk. The determination of precursors is imperative to ensure the efficiency of the early warning technique. Herein, a controllable magnetic adsorbent FeO/ZIFs was first introduced for the effective extraction and determination of averantin (AVN) and sterigmatocystin (ST) precursors in cereal by combining magnetic solid-phase extraction (MSPE) and high-performance liquid chromatography (HPLC). Benefiting from the abundant adsorption sites and multifunctional groups matching the analytes, FeO/ZIFs effectively and simultaneously extracted AVN and ST with great differences in polarity and structure via multiple interactions. AVN was extracted by FeO/ZIFs mainly through π-π and hydrophobic interactions, while ST was extracted predominantly by electrostatic interactions and surface complexation. The limits of detection were 0.08 μg kg (AVN) and 0.36 μg kg (ST). The developed method exhibited satisfactory spiked recoveries (79.1%-105.4%) in the determination of AVN and ST in rice. This work provides a novel analytical strategy for further studying AFB early warning technique and the formation and transformation of aflatoxins.