Development of a magnetic molecularly imprinted polymer for the removal of dexamethasone from river nile water

Magnetic molecularly imprinted polymers (MMIPs) were synthesized using 3-aminophenylboronic acid (APBA) for recognition of dexamethasone (DEX). The particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis, Barrett-Joyner-Halenda (BJH) pore size distribution, and X-ray photoelectron spectroscopy (XPS). Kinetic evaluation showed pseudo-first-order (PFO) behavior with rapid uptake within 7 min and equilibrium at 120 min, while Langmuir modeling gave a maximum adsorption capacity of q_max = 500.0 µmol g⁻¹. The optimized polymer exhibited 67.0% binding in rebinding experiments. Magnetic solid-phase extraction (MSPE) was conducted using 20 mg sorbent and 3 mL sample, giving 90.08% ± 7.25% recovery in River Nile water with an imprinting factor (IF = 2.21). Greenness evaluation gave a solvent intensity (SI) of 3.5 mL per sample and an analytical method volume intensity (AMVI) of 9.0 mL. EcoScale (~ 89) placed the synthesis in the excellent category, with AGREEmip (0.63) indicating good compliance with green principles, while the MSPE workflow showed favorable greenness (EcoScale = 77; AGREEprep = 0.51). DEX was quantified using a newly developed and validated ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method. This APBA-based MMIP-MSPE workflow offers a rapid and environmentally compatible approach for DEX monitoring.