Magnetic solid phase extraction of glyphosate and aminomethylphosphonic acid in river water using Ti⁴⁺-immobilized Fe₃O₄ nanoparticles by capillary electrophoresis

The residual glyphosate (GLYP) in the environment is harmful to human health. Monitoring GLYP and its major metabolite aminomethylphosphonic acid (AMPA) in a complicated matrix is an important analytical task. Based on the affinity of phosphate groups to metal ions, iron oxide nanoparticles immobilized with Ti⁴⁺ using polydopamine (PDA) as bridging molecules (Fe₃O₄@PDA-Ti⁴⁺ NPs) were employed to develop a magnetic solid phase extraction (mSPE) method for GLYP and AMPA by electrostatic interaction. After extraction with Fe₃O₄@PDA-Ti⁴⁺ NPs and elution for 5 min, the purified and enriched analytes were derivatized, prior to CE with diode array UV detection. Relying on the coupled mSPE-CE method, the detection limits were 0.4 ng mL⁻¹ for GLYP and AMPA. The present method was employed to monitor GLYP and AMPA in a Roundup® sample and river water sample, revealing its good possibilities for applicability. Herein, by virtue of the immobilized metal affinity extraction (IMAE), the coupled mSPE-CE method would be effective, easy to operate and applicable for analyzing herbicides in environmental samples.