[Simultaneous detection of 34 pesticide and metabolite residues in vegetables and fruits using improved QuEChERS-gas chromatography-tandem mass spectrometry with carboxylated multi-walled carbon nanotubes].

With the rapid advancement of industrialization， agricultural intensification， and urbanization， issues pertaining to environmental pollution and food safety have become increasingly prominent. The use of pesticides plays a vital role in augmenting agricultural yield and quality， thereby serving as a foundational element of modern agriculture. However， improper or excessive application can lead to pesticide residues， which pose a significant threat to ecological systems and human health. Therefore， it is essential to enhance the surveillance of pesticide residue levels and to pioneer novel， efficient analytical methodologies. Sample pretreatment constitutes a crucial stage in the detection pipeline. Consequently， the development of rapid， green， and efficient sample pretreatment techniques has advanced significantly and gained widespread application in recent years. To effectively monitor pesticide residues in fruits and vegetables while reducing matrix interference， we established a high-throughput method for detecting 34 pesticides and their metabolites. This method utilizes a modified QuEChERS approach with carboxylated multi-walled carbon nanotubes （MWCNTs-COOH） as a clean-up sorbent， followed by analysis with gas chromatography-tandem mass spectrometry （GC-MS/MS）. The detection conditions for 34 pesticide and metabolite residues in fruits and vegetables were established through the optimization of the pretreatment process， chromatographic conditions， and mass spectrometry parameters. Specifically， fruit and vegetable samples were homogenized and extracted using a commercial QuEChERS EN extraction kit. Following shaking and centrifugation， the supernatant was transferred to a purification tube containing 10 mg of MWCNTs-COOH. Subsequently， this supernatant was evaporated to near-dryness under a gentle stream of nitrogen， reconstituted in ethyl acetate containing an internal standard， and filtered through a 0.22 μm nylon membrane filter. The target substances were separated on a HP-5MS UI quartz capillary column （30 m×0.25 mm×0.25 μm） with a programmed temperature gradient， detected by GC-MS/MS in multiple reaction monitoring （MRM） mode， and quantified using a matrix-matched internal standard calibration method. A full scan was performed across an