Target and suspect screening of pesticide residues in soil samples from peach orchards using liquid chromatography quadrupole time-of-flight mass spectrometry

Agricultural soil contamination by pesticide residues has become a serious issue of increasing concern due to their high persistence and toxicity to non-target species. However, as the world's largest peach producer, national scale surveys on pesticide residues in peach orchard soils are scarce in China. In this study, a target and suspect screening method covering over 200 pesticides commonly used in peach orchards was developed using ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry in MSE. An identification strategy using different data processing parameters was developed to identify the pesticide occurrence in soil. The method was applied to soil samples from typical peach orchards in 12 regions across China. The present work also discusses in detail the frequency of occurrence, concentration of pesticides, spatial distribution of multiresidues, and relationship between pesticide occurrence and soil properties. In the tested soil samples, 21 herbicides (level 1), 31 fungicides (level 2a), 24 insecticides (level 2a), and 3 growth regulators (level 2a) were identified. The total concentrations of quantifiable herbicides in the soil samples ranged from 1.05 to 327 ng/g. Only in 5.4% of the soil samples, no pesticide residues were present. By contrast, more than 86% of the total contained multiple residues. This study represents the first large-scale survey of pesticides in soil from peach orchards and provides comprehensive and accurate information on the pesticide residue status for risk assessment.