Single laboratory validation of a SPE method for the determination of PAHs in edible oils by GC-MS

Abstract

This article describes a method for the quantification of seven Polycyclic Aromatic Hydrocarbons (PAHs) in edible oils (soy, sunflower and olive). It involved the application of a low-volume liquid–liquid extraction (LLE) technique followed by a solid-phase extraction (SPE) clean-up with C₁₈ and silica cartridges. Separation and analysis of compounds were performed by gas chromatography coupled to mass spectrometry (GC-MS). ¹³C-labeled PAHs as internal standards were used to aid the identification of compounds and to determine the efficiency of the extraction method in an isotope dilution mass spectrometry (IDMS) approach. Low-volume LLE and SPE clean-up procedures allowed the reduction of solvent consumption, eliminated the necessity of a previous saponification step and provided less sample preparation time when compared to traditional PAHs extraction and clean-up methods. The analytical procedure was validated according to recommendations of the European Commission Decision 2002/657/EC and European Commission Regulations (2007/333/EC and 2011/836/EU). Acceptable values (except for chrysene) were obtained for the following parameters: linearity (r² > 0.98), limit of quantification (0.12 < LOQ < 0.68 μg kg⁻¹), limit of detection (0.04 < LOD < 0.23 μg kg⁻¹), trueness (recovery rates and certified reference material normalized error), and precision (repeatability and intermediate precision). Recoveries higher than 80% were attained for seven PAHs, at three concentration levels (0.75, 2.00 and 4.00 μg kg⁻¹). This validated method will be used by the Ministry of Agriculture, Livestock and Food Supply in Brazil.