Modified QuEChERS strategy based on dynamic in-situ assembly of aminated single-walled carbon nanotubes and magnetic Fe3O4 nanoparticles for pesticide residue analysis in Rhizoma Polygonati.

Accurate quantification of pesticide residues is critical to ensure the quality and safety of Rhizoma Polygonati, a well-recognized medicine-food homologous herb widely applied in functional food development. Strong matrix interference in gas chromatography-tandem mass spectrometry (GC-MS) detection and notable quantitative bias are frequently induced by the abundant pigments, polysaccharides, saponins and endogenous components in the herbal matrix. Conventional PSA and C18 adsorbents in standard QuEChERS protocols exhibit restricted purification capacity for this complex matrix, while most documented magnetic carbon-based adsorbents demand tedious pre-synthesis procedures that may block the active adsorption sites of nanomaterials. A modified QuEChERS-GC-MS method coupled with dynamic in-situ assembly strategy was established for 12 pesticide residues in Rhizoma Polygonati. Without pre-synthesis of any composites, in-situ functional synergy between NH2-SWCNTs and magnetic Fe3O4 nanoparticles was achieved during the dispersive solid-phase extraction (d-SPE) step. Superior purification performance to conventional adsorbents was obtained by this system, with the matrix effect range of target pesticides narrowed from -31.4%-64.3% to -25.3%-36.7%. Favorable linearity (R ≥ 0.9990), acceptable spiked recoveries (86.2%-106.5%) and stable precision (RSD ≤ 15.20%) were validated through systematic method validation, providing a feasible and robust analytical protocol for pesticide residue monitoring in Rhizoma Polygonati and other complex herbal matrices.