A water compatible magnetic molecularly imprinted nanocomposite for the class-selective enrichment of quinoxaline-1,4-dioxides in environmental water.

In this work, a novel water compatible core-shell magnetic molecularly imprinted nanocomposite (Fe₃O₄-COOH@MIPs) was synthesized in an acetonitrile-water reaction system by adopting carboxyl group-functionalized Fe₃O₄ nanoparticles as the magnetic core, olaquindox as the template molecule and acrylamide as the functional monomer. The resulting Fe₃O₄-COOH@MIPs was characterized and applied as an adsorbent for magnetic solid-phase extraction (MSPE) of three quinoline-1,4-dioxides (QdNOs). The Fe₃O₄-COOH@MIPs possessed strong magnetic responsiveness, fast adsorption equilibrium rate (equilibrium within 5 min) and excellent selectivity. By coupling Fe₃O₄-COOH@MIPs based MSPE with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), good linearity (R² ≥ 0.9985) and low limits of detection (0.83-5.0 ng L^-1) for QdNOs were obtained. Finally, the proposed method was applied to determine trace QdNOs in environmental water samples, and the recoveries were in the range of 68.08-99.88% with RSD less than 12.5%.