A dilute-and-inject liquid-gas chromatography-mass spectrometry method for the analysis of sixteen polycyclic aromatic hydrocarbons in extra-virgin olive oil.

ABSTRACT

BACKGROUND: Polycyclic aromatic hydrocarbons (PAHs) represent a diverse group of organic compounds characterized by the fusion of two or more benzene rings arranged in various structural forms. Due to their harmful effects on human health, it is essential to implement monitoring systems and preventive measures to regulate human exposure. Given the affinity of PAHs for lipids, extensive research has been focused on their presence in vegetable oils. This study aimed to develop an on-line liquid-gas chromatography (LC-GC) method (using tandem mass spectrometry) with minimized solvent consumption for the determination of 16 PAHs in extra-virgin olive oil (EVOO). RESULTS: A side-by-side comparison of the selected-ion-monitoring and the pseudo multiple-reaction-monitoring (p-MRM) acquisition modes was performed, in terms of specificity and detectability. The results obtained using the p-MRM mode were superior, and for this reason it was selected. The method was linear over the concentration range 1-200 µg kg-1 (except in five cases, over 2-200 and 5-200 µg kg-1 ranges). Accuracy (at the 2 µg kg-1 and 20 µg kg-1 concentration levels) was in the 86.9-109.3 % range, with an RSD <10 %. Intra-day and inter-day precision (at 2 µg kg-1 and 20 µg kg-1 concentration levels) were in the 1.2-9.7 % and 3.2-10.8 % ranges, respectively. For all the PAHs, a negative matrix effect was observed. Three out of sixteen PAHs were detected in three EVOOs (among ten samples), albeit at the low ppb level. Limits of quantification were satisfactory in relation to EU legislation on the presence of PAHs in vegetable oils. SIGNIFICANCE: A dilute-and-inject LC-GC-tandem mass spectrometry method is herein proposed fulfilling EU legislation requirements; sample preparation was very simple, inasmuch that it involved only a dilution step, thus avoiding extraction, clean-up, and thus a high consumption of organic solvents. In fact, considering both oil dilution and the LC mobile phase, less than 8 mL of solvents were used.