Synthesis of magnetic metal organic framework/covalent organic framework hybrid materials as adsorbents for magnetic solid phase extraction of four endocrine disrupting chemicals from milk samples

Rationale Endocrine disrupting chemicals (EDCs), widespread and easily ingested through simple food chain, have been suggested to pose potential carcinogenic threats to human health. Considering food safety and public health, it is urgent to establish sensitive and effective method to enrich and determine EDCs in food samples. Methods Novel hybrid nanocomposites Fe3 O4 @A-TpBD@NH2 -MIL-125(Ti) were synthesized through the formation of amide bonds. The as-prepared Fe3 O4 were innovatively encapsulated with 4-aminobenzoic acid-functionalized COF(A-TpBD) to generate bare carboxyl (-COOH), which formed amide bonds with the NH2 -MIL-125(Ti), generating well-defined and hierarchical hybrid materials. The Fe3 O4 @A-TpBD@NH2 -MIL-125(Ti) materials were used as magnetic solid-phase extraction (MSPE) adsorbents that were coupled with high-performance liquid chromatography-tandem mass spectrometry (HPLC/MS/MS) to enrich and determine EDCs (E1, E2, E3 and BPA) from milk samples. Results Fe3 O4 @A-TpBD@NH2 -MIL-125(Ti) exhibited improved adsorption efficiency and selectivity based on π-π stacking, hydrogen bonding, electrostatic interactions and the interaction between hydroxyl group in EDCs and titanium ions (IV, [Ti]4+ ). Under the optimized conditions, Fe3 O4 @A-TpBD@NH2 -MIL-125(Ti)-based MSPE coupled with HPLC/MS/MS showed good linearity with correlation coefficient (R2 ) ≥ 0.9983 and high sensitivity with LODs in the range of 0.37-0.85 μg/L. Moreover, the developed method was successfully employed to detect EDCs in milk samples. Conclusions Fe3 O4 @A-TpBD@NH2 -MIL-125(Ti) possess good adsorption capability and selectivity for EDCs. In addition, the proposed MSPE-HPLC/MS/MS method based on Fe3 O4 @A-TpBD@NH2 -MIL-125(Ti) is effective and sensitive for the determination of EDCs in real samples, and can be used as a robust alternative method for monitoring EDCs in complex matrixes.