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Updated: May 22, 2026
Analysis of Organochlorine Pesticides in a Soil Sample by a Modified QuEChERS Approach Using Ammonium Formate
Published on: January 20, 2023
Extensive validation and implementation of a modified QuEChERS method for the analysis of 24 pesticides in leek by
Xiaozhuo Wang1, Ziyi Liu2, Zhi Chen3
1Division of Chemical Metrology and Analytical Science, National Institute of Metrology, Beijing, 100029, China; Key Laboratory of Chemical Metrology and Applications on Nutrition and Health, State Administration for Market Regulation, Beijing, 100029, China; College of Materials and Chemistry, China Jiliang University, 258 Xueyuan Street, Xiasha Higher Education Zone, Hangzhou, 310018, China.
Abstract:
This study presents the development and validation of a highly accurate high-throughput method for the simultaneous determination of 24 representative pesticides in leek samples. The approach integrates a matrix-tailored QuEChERS procedure with complementary low-pressure gas chromatography and ultra-performance liquid chromatography, both coupled to isotope dilution tandem mass spectrometry (LPGC-MS/MS and UHPLC-MS/MS). A systematic investigation of rapid dual-chromatographic separation, sample preparation workflow and hybrid classic/computation-aided calibration strategy was undertaken to maximize analyte recovery and suppress bias. The developed strategy effectively compensated for matrix-induced signal perturbations, reducing matrix effects to within ±20% for GC and ±10% for LC analyses. Comprehensive validation according to SANTE guidelines demonstrated high accuracy (93-111% for GC, 94-105% for LC), sensitivity (LOQ ≤10 μg/kg for most analytes), and precision (RSD <6%). The method's performance was established through its critical applications: i) assigning certified values to a leek matrix reference material with low relative expanded uncertainties (5-10%, k = 2); ii) serving as the reference method in seven proficiency testing schemes to ensure inter-laboratory comparability; and iii) screening 47 commercial leek samples. This survey revealed a 98% pesticide detection frequency and a 51% exceedance rate of EU maximum residue limits, highlighting significant food safety concerns, particularly for pyrethroids and neonicotinoids.
