Micro-matrix cartridge extraction followed by online micro-solid phase extraction based on polystyrene@hydroxypropyl-β-cyclodextrin nanofibers for selective determination of fipronil and its metabolites in soil

Micro-matrix cartridge extraction coupled on-line to micro-solid phase extraction-high performance liquid chromatography-mass spectrometry (μ-MCE-online-μ-SPE-HPLC–MS) is presented. Micro-matrix cartridge extraction (μ-MCE) was applied to highly efficient desorption of adsorbed pesticides from contaminated soil with favorable extraction efficiency (100%). Novel polystyrene@hydroxypropyl-β-cyclodextrin (PS@HPCD) electrospun nanofibers with 3D network structure were prepared to selectively capture fipronil and its metabolites. High selectivity was obtained with adsorption efficiency ≥ 86.64% via complexation, hydrophobic affinity, and π-π interactions. PS@HPCD nanofibers exhibited remarkable advantages such as excellent enrichment factors (24–55), superior permeability, and long service life (> 65 times). Under the optimum conditions, wide linear range (0.1–1000 ng g⁻¹), low detection limits (0.0032–0.0067 ng g⁻¹), high recoveries (84–124.5%), favorable repeatability (RSD ≤ 10.4%, n = 5), and reproducibility (RSD ≤ 7.2%, n = 3) were acquired for fipronil and three metabolites. The developed method was applied to the pesticide determination in actual soils and the ISO-certified soil with satisfactory recoveries (96.5%). The method developed provides a green, efficient, and miniaturized method for the determination of trace pesticide residues in soil. Graphical