Development and validation of modified QuEChERS- GC/MS method for simultaneous determination of current-use pesticide residues in soil

Abstract

Pesticide residues in soil pose potential risks to ecosystems and human health, necessitating reliable and efficient analytical methods for their determination. This study developed and validated a modified QuEChERS-based extraction procedure combined with gas chromatography-mass spectrometry (GC/MS) for the simultaneous analysis of eight commonly used pesticides in soil, including herbicides, insecticides, and fungicides. Key extraction parameters were optimised for soil matrices, focusing on solvent composition and primary-secondary amine (PSA) clean-up levels. Optimal performance was achieved with 1% acetic acid in acetonitrile and 25 mg PSA per 1 mL of extract. The method was validated according to European Commission SANTE guidelines, demonstrating good linearity (R² > 0.99), low limits of detection (3–8 µg/kg), acceptable recoveries (69–114%), and satisfactory repeatability (RSD < 13%). The validated procedure was successfully applied to agricultural soil samples from central Vietnam, where residues of pretilachlor, fluazifop-p-butyl, and trifloxystrobin were detected. The results confirm that the proposed method is reliable, cost-effective, and suitable for routine monitoring of pesticide residues in soil.