Determination of Selected Pesticide Residues in Wheat Flour by GC–MS

The widespread use of pesticides in modern agriculture contributes to a range of environmental and food-safety concerns, including the persistence of chemical residues in food products, contamination of soil and water, and potential risks to human and ecosystem health. Among food and feed commodities, cereal-based products represent an important potential source of dietary exposure due to their extensive consumption and the possibility of residue transfer from wheat grains to processed flours. In this study, a direct acetone extraction combined with gas chromatography–ion-trap mass spectrometry (GC–MS) was explored as a simplified analytical approach for the determination of selected pesticide residues in wheat flour. Nine pesticides were initially screened, and six compounds (ethoprophos, dimethoate, terbufos, diazinon, chlorpyrifos, and methoxychlor) were retained for method development based on their extractability and chromatographic behavior. Chromatographic and ionization conditions were optimized in Full Scan, SIM, and MS/MS modes, and matrix-matched calibration was applied to compensate for matrix-induced signal variations. The method was evaluated in a composite wheat-flour matrix, demonstrating acceptable process efficiency, a characterized matrix effect, and satisfactory quantitative performance for four analytes over the experimentally evaluated range of 5–50 µg/kg. Two commercial flour samples contained estimated diazinon concentrations of 0.4 and 1.0 µg/kg, respectively, which were further assessed using the standard addition method. Overall, this study provides a proof of concept for the use of direct acetone extraction coupled with ion-trap GC–MS for the exploratory monitoring of selected pesticide residues in wheat flour. Full method validation in accordance with SANTE/11312/2021 v2026 was outside the scope of this work.