Modified QuEChERS coupled with hybrid mass spectrometry for 322 target pesticides and suspect screening of emerging organic contaminants in agricultural soils

Pesticide application is a common agricultural practice for controlling pests, weeds, and diseases, but it often leaves residues in soils, posing risks of crop uptake, environmental contamination, and human exposure. Regular and accurate monitoring of soil pesticide residues is therefore essential for effective management. However, current analyses are typically limited to a narrow range of pesticides and soil properties. In parallel, emerging organic contaminants, frequently detected in soils due to anthropogenic activities and potentially harmful to human health, are usually studied separately rather than alongside pesticide residues. Therefore, this study developed a modified QuEChERS method, integrating gas and liquid chromatography with low-resolution tandem mass spectrometry (GC-QqQ-MS/MS and LC-QqQ-MS/MS), for the analysis of 322 target pesticides in soils. Additionally, high-resolution tandem mass spectrometry (LC-QTOF/MS) was employed for the suspect screening of pesticides beyond the target list, as well as emerging organic contaminants. The optimized method achieved acceptable recoveries (60-140 %) and relative standard deviations (≤20 %) for all 322 pesticides across three tested loam and sandy loam soils (3.2-5.4 % organic matter). Method detection limits ranged from 6.0 × 10-4 to 4.2 µg kg-1, with most pesticides quantifiable below 1.0 µg kg-1. Application of the validated method to 44 farmland soils with documented pesticide use confirmed most recorded pesticides, revealed several unrecorded ones, and tentatively identified 35 pesticides and 10 emerging organic contaminants. These findings demonstrate the methodology's robustness and broad applicability across diverse soil properties, providing critical data to support pesticide management, track emerging contaminant distribution, and promote agricultural sustainability.