Single-laboratory validation of a GC/MS method for the determination of 27 polycyclic aromatic hydrocarbons (PAHs) in oils and fats

Abstract

A protocol for the measurement of 27 polycyclic aromatic hydrocarbons (PAHs) in vegetable oils by GC/MS has undergone single-laboratory validation. PAHs were measured in three oils (olive pomace, sunflower and coconut oil). Five samples of each oil (one unfortified, and four fortified at concentrations between 2 and 50 µg kg−1) were analysed in replicate (four times in separate runs). Two samples (one unfortified and one fortified at 2 µg kg−1) of five oils (virgin olive oil, grapeseed oil, toasted sesame oil, olive margarine and palm oil) were also analysed. The validation included an assessment of measurement bias from the results of 120 measurements of a certified reference material (coconut oil BCR CRM458 certified for six PAHs). The method is capable of reliably detecting 26 out of 27 PAHs, at concentration <2 µg kg−1 which is the European Union maximum limit for benzo[a]pyrene, in vegetable oils, olive pomace oil, sunflower oil and coconut oil. Quantitative results were obtained that are fit for purpose for concentrations from <2 to 50 µg kg−1 for 24 out of 27 PAHs in olive pomace oil, sunflower oil and coconut oil. The reliable detection of 2 µg kg−1 of PAHs in five additional oils (virgin olive oil, grapeseed oil, toasted sesame oil, olive margarine and palm oil) has been demonstrated. The method failed to produce fit-for-purpose results for the measurement of dibenzo[a,h]pyrene, anthanthrene and cyclopenta[c,d]pyrene. The reason for the failure was the large variation in results. The likely cause was the lack of availability of 13C isotope internal standards for these PAHs at the time of the study. The protocol has been shown to be fit-for-purpose and is suitable for formal validation by inter-laboratory collaborative study.