Quechers extraction and a straightforward clean-up procedure for the quantification of polycyclic aromatic hydrocarbons (PAHS) in ripened cheese using GC-MS/MS

Polycyclic Aromatic Hydrocarbons (PAHs) are chemicals made up of hydrogen and carbon atoms arranged in two or more fused aromatic rings. Over a hundred different PAH compounds exist, typically in complex mixtures. These compounds are known environmental carcinogens and can originate from both human activities and food processing. For non-smokers, the primary route of PAH exposure is through food consumption. Due to their lipophilic nature, PAHs can easily accumulate in fatty food matrices such as milk, meat, edible oils, fish, and cheese. This study aimed to develop an effective and straightforward sample preparation procedure for the determination of PAHs in ripened cheese samples. For this study, 60 samples of non-smoked hard cheese were collected from the market. The optimized protocol for PAH quantification consisted of three steps: 1) a rapid QuEChERS extraction using cyclohexane as the solvent, 2) a quick and efficient mechanical clean-up with Silica Gel (70-200 mesh ASTM), and 3) concentration under a gentle stream of nitrogen. PAH analysis was performed using an Agilent Intuvo 9000 GC system coupled with an Agilent 7000 Series Triple Quadrupole MS, employing a HP-5MS Ultra Inert capillary column (30 m × 0.32 mm id × 0.25 μm film thickness). Chromatograms were acquired in selected-ion monitoring (SIM) mode, and target compounds were identified based on their ions and retention times. Eighteen different PAHs were considered for method development: naphthalene (NaP), 2-methylnaphthalene (MeNaP2), 1-methylnaphthalene (MeNaP1), acenaphthene (Ace), acenaphthylene (Acp), fluorene (Flu), phenanthrene (Phen), anthracene (Ant), fluoranthene (Fla), pyrene (Pyr), benzo[a]anthracene (B[a]a), chrysene (Chr), benzo[b]fluoranthene (B[b]f), benzo[k]fluoranthene (B[k]f), benzo[a]pyrene (B[a]p), indeno[1,2,3-c,d]pyrene (I[cd]p), dibenzo[a,h]-anthracene (D[ah]a), and benzo[g,h,i]perylene (B[ghi]P). Once validated for linearity, repeatability, reproducibility, recovery, limit of detection (LOD), and limit of quantification (LOQ), the method was applied to analyze the entire set of collected samples. In three cheese samples were identified and quantified the lower molecular weight PAHs: NaP, MeNaP2 and MeNaP1. However, the degree of contamination in these samples was very low, with the total concentration not higher than 30 μg/kg. The experiments conducted in this study demonstrated that the proposed method effectively clean-up the sample while achieving acceptable recoveries, repeatability, and reproducibility for PAH quantification in cheese. Therefore, this method could be successfully applied to different food matrices with high fat content.