Preparation of molecularly imprinted polymers based on core-shell magnetic mesoporous silica and application in the...

A selective adsorbent was fabricated and evaluated for its applicability to trace E₂ analysis by grafting a molecularly imprinted polymeric shell onto a magnetic nanoparticle encased in a mesoporous SiO₂ layer (denoted Fe₃O₄@mSiO₂@MIP) with E₂ as the imprinting template. The morphology and microstructure of the resulting Fe₃O₄@mSiO₂@MIP were characterized by scanning electron microscopy and transmission electron microscopy, and its functional groups were determined by Fourier-transform infrared spectroscopy. Its adsorption performance was investigated through kinetic, thermodynamic, and selectivity studies, and relevant models were adopted to interpret the adsorption mechanism. Adsorption followed pseudo-second-order kinetics and was well described by the Freundlich isotherm, yielding a capacity of 4.01 mg g^-1 within 30 min together with a notable imprinting factor (2.36). Compared with the control non-imprinted material (Fe₃O₄@mSiO₂@NIP), the imprinted sorbent (Fe₃O₄@mSiO₂@MIP) exhibited markedly enhanced adsorption toward E₂. Under the optimized magnetic solid-phase extraction (MSPE) conditions, an MSPE-HPLC-UV method was established for determining E₂ residues in egg and milk samples. The method achieved an enrichment factor of 36 with satisfactory recoveries ranging from 86.7% to 101.2%. Furthermore, the prepared Fe₃O₄@mSiO₂@MIP could be regenerated and reused for at least seven cycles, confirming its feasibility for practical use.