Novel hydrocortisone magnetic molecularly imprinted polymers: Preparation, characterization, and application

•Pretreatment of complex samples by magnetic molecularly imprinted polymer.•Use high performance liquid chromatography to detect the content of hydrocortisone.•Effective treatment of trace hydrocortisone in milk and milk powder.•The rapid adsorption and elution of polymers are applicable to the market. In this work, magnetic molecularly imprinted polymers (MMIPs) were prepared by a surface imprinting method using Fe3O4 nanoparticles as a support. The products were characterized by FT-IR spectroscopy, VSM, TGA, SEM, and TEM. Combined with HPLC, hydrocortisone in milk powder and milk were separated and purified, and their contents were monitored. The results showed that MMIPs with a particle size of approximately 1000 nm were successfully prepared. The adsorption mechanism of MMIPs was confirmed by kinetic adsorption and thermodynamic adsorption experiments; the maximum adsorption capacity was found to be 17.2 mg g−1, and adsorption equilibrium could be reached within 40 min. In the actual sample application, the recovery rates of milk powder and milk were 93.88–99.15% and 95.80–98.10%, respectively. These results showed that MMIPs had good performance in selectively identifying hydrocortisone and were suitable for determining hydrocortisone in milk products.