Determination of pesticide residues in oat flour using low-temperature partition extraction and GC–MS analysis

Abstract

A simple method based on solid–liquid extraction with a low-temperature partition (SLE/LTP) and analysis by gas chromatography coupled to mass spectrometry (GC–MS) was optimized and validated for determining residues of the pesticides triadimenol, flutriafol, λ-cyhalothrin, difenoconazole, and azoxystrobin in oat flour. A factorial design was employed to optimize the technique and establish the best conditions for the simultaneous extraction of the analytes. Acetonitrile-sample extraction and its 4 h freezing made it possible to recover the pesticides and clean the extracts in a single step. The limit of detection ranged from 1.72 to 12.9 μg kg⁻¹, and the limit of quantification from 5.73 to 43.0 μg kg⁻¹. These values are below the maximum residue limit (MRL) permitted by National legislation. The recovery percentage fell between 91.7 and 108%, with coefficients of variation under 12%. The validated method was applied to oat flour samples randomly acquired from the local market of Viçosa (Minas Gerais, Brazil) and no residues were detected. The SLE/LTP–GC–MS method proved simple, efficient, selective, and sensitive for determining pesticide residues from oat flour samples, offering a more simplified approach compared to techniques described in the literature.