Magnetic Fe3O4@rGO-Ag SERS platform for rapid sub-micromolar detection of triazophos in complex food matrices

Abstract

Triazophos (Tri), a persistent organophosphorus pesticide, poses significant risks on the ecosystems and food safety. Though chromatography-mass spectrometry achieves excellent sensitivity, its cost, training demands and long sample work-up preclude on-site use. Herein, we introduce a magnetic solid-phase micro-extraction SERS platform (Fe₃O₄@rGO-Ag) that couples superparamagnetic isolation (<1 s) with rGO pre-concentration and Ag-nanoparticle plasmonic enhancement. Tri is quantified in 40 min with a limit of detection (LOD) of 0.012 μM (10× lower than direct SERS) and linearity from 1 to 100 μM (R² = 0.9932). Kinetic modeling and X-ray photoelectron spectroscopy confirm that reversible physisorption dominates Tri enrichment. In complex food matrices (e.g., Brassica campestris L. and mango), the method delivers recoveries of 99–117 % with relative standard deviation (RSD) less than 6.8 % and retains 97 % of the SERS signal in the presence of common interferents. This work bridges the critical gap between laboratory-grade sensitivity and field-deployable practicality in pesticide monitoring. The protocol's magnetic isolation, reversible enrichment mechanism, and user-friendly optical readout make it easier to perform rapid, on-site quantitative screening at farms and markets, thereby reducing the risk of contaminated produce reaching consumers and mitigating ecological exposure to persistent organophosphorus residues.