Magnetic metal-organic cage for high-efficiency magnetic solid phase extraction of four aflatoxins from food matrices

Aflatoxins (AFs) in complex matrices like tea and peanuts pose significant food safety concerns. This work describes the synthesis and application of a novel magnetic metal-organic cage (MOC), Fe₃O₄@ZrT-3-(NH₂)₂, derived from 3,3''-diamino-[1,1':4',1''-terphenyl]-4,4''-dicarboxylic acid (DATPDA), for the magnetic solid-phase extraction (MSPE) of four major AFs (AFB₁, AFB₂, AFG₁, AFG₂). The Fe₃O₄@ZrT-3-(NH₂)₂ exhibited high adsorption capacities (48.57-53.14 mg/g), excellent reusability (>8 cycles with >80.78% recovery), and notably, superior performance under acidic conditions (optimum pH 4). Adsorption behavior fitted Langmuir isotherm and pseudo-second-order kinetics, suggesting monolayer chemisorption. The optimized MSPE procedure (6 mg of adsorbent, 3 min adsorption, 4 min desorption), achieving a 5-fold enrichment factor, coupled with UPLC-MS/MS achieved low limits of detection (0.0023-0.0072 µg/kg) and satisfactory recoveries (82.32-103.53%) in tea and peanut samples. This developed method demonstrates significant potential for rapid, sensitive, and reliable AFs determination in challenging food matrices.