Integration of Fe3O4@UiO-66-NH2@MON core-shell structured adsorbents for specific preconcentration and sensitive determination of aflatoxins against complex sample matrix

Aflatoxins have been a hot topic in the field related into public health and ecosystem protection, and great effort has been made in developing of adsorptive materials for effective probing the target aflatoxins. Conventional materials, like metal-organic frameworks (MOFs) showed promising application in separation science. However, the cumbersome separation process, competitive adsorption are also major challenges. Regarding this, a novel magnetic micro-composite denoted as Fe3O4@UiO-66-NH2@MON with core-shell structure was constructed. The core of Fe3O4 microspheres was coated with MOFs crystals, and then microporous organic network (MON) was introduced onto the surface of Fe3O4@UiO-66-NH2 through a sonogashira coupling reaction. It exhibited good magnetic separation ability, which effectively simplified the pre-treatment steps. The proposed method possessed excellent selectivity and sensitivity, with detection limits in the range of 0.15-0.87 μg L−1 combination with HPLC analysis. More importantly, the MON coating significantly improved the hydro-stability of whole adsorbents, thus enhancing the adsorption efficiency and favoring the practical application of the materials. The developed Fe3O4@UiO-66-NH2@MON-based solid extraction method has been well-applied for real sample analysis, with the recovery of 87.3%–101.8%. We believe the newly-constructed hybrid nano-adsorbents hold great potential in further application in various analytical methods for different target analytes.