Quantification of multi-class pesticides in wipes dust by liquid chromatography - mass spectrometry: development and application in rural households

Pesticides used in agricultural or domestic activities contaminate the outdoor environment, and subsequently infiltrate homes, where they accumulate in indoor dust. Household dust may serve as a useful proxy for assessing human exposure to pesticide residues. However, simultaneously quantifying a wide range of molecules with diverse chemical properties remains analytically challenging. This study developed and validated a liquid chromatography-mass spectrometry method to quantify 95 pesticides from different chemical families (neonicotinoids, azoles, organophosphates, carbamates, organochlorines) in wipe-collected dust samples. Solvent optimization identified ethyl acetate as the most effective for extraction. Quantification relied on linear regression with calibration ranges of 0.052 to 1.67 μg/g of dust for 81 pesticides and 0.167 to 1.67 μg/g of dust for 14 pesticides. Method validation assessed limit of quantification (LOQ), precision, accuracy, carry-over, dilution integrity, matrix effects (ME) and recovery, following European Medicines Agency guidelines. Intra- and inter day-precision and accuracy were lower than 20% at LOQ and 15% for higher QC levels. ME due to ion suppression were corrected using internal standards. The validated method was applied to dust collected from households in the LTSER Zone Atelier Plaine & Val de Sèvre (France) by rubbing a 100 cm² wipe over a 20 × 20 cm template. The most frequently detected compounds were insecticides imidacloprid, chlorpyrifos, and the fungicide azoxystrobin. This rapid, cost-effective, and easy-to-implement wipe method provides a valuable tool for assessing indoor pesticide contamination. Further studies should explore whether indoor dust concentrations reliably reflect internal human exposure.