Abstract: Based on gel permeation chromatography-gas chromatography-tandem mass spectrometry (GPC-GC-MS/MS), an analytical method was established for the simultaneous determination of 20 banned pesticide residues in Astragalus membranaceus (Fisch.) Bunge. The results showed that the purification effect of GPC was superior to Florisil, N-Al₂O₃ and C18. GPC effectively removed interfering substances such as lipids and pigments, significantly reduced baseline noise, enhanced the response intensity of target compounds, and improved detection sensitivity. The method demonstrated good linearity in the concentration range of 0.01-0.50 μg/mL (R²>0.990 0), with limits of detection (LOD) of 0.001-0.003 mg/kg and limits of quantification (LOQ) of 0.003-0.010 mg/kg. The recovery rates of organochlorine pesticides were generally higher than those of organophosphorus pesticides. The relative standard deviations (RSD) of both types of pesticides were the lowest at the medium spiked concentration (0.10 mg/kg), but increased at both low (0.01 mg/kg) and high (0.50 mg/kg) spiked concentrations, reflecting differentiated impacts of matrix effects and potential interferences at different concentration levels. The method exhibited satisfactory sensitivity, with both LOD and LOQ meeting the requirements for pesticide residues detection. It not only complied with the relevant regulations of the 2020 edition of the Chinese Pharmacopoeia, but was also suitable for pesticide residues screening in the export trade of Astragalus membranaceus (Fisch.) Bunge. This method significantly improved pesticides recovery rates, effectively removed matrix interferences such as fat-soluble pigments, reduced matrix effects, and was applicable for pesticide residues monitoring in Astragalus membranaceus (Fisch.) Bunge and other traditional Chinese medicines with highly complex matrices.

Key words: gel permeation chromatography, gas chromatography-tandem mass spectrometry, Astragalus membranaceus (Fisch.) Bunge, banned pesticides, residues