Direct Immersion SPME-GC-MS Method for Polycyclic Aromatic Hydrocarbons Determination in Edible Oil 

Giorgia Purcaro, Massimo Picardo, Sabrina Moret, Lanfranco S. Conte
University of Udine

Polycyclic aromatic hydrocarbons (PAHs) are a group of organic compounds produced through incomplete combustion or pyrolysis of organic matter. The occurrence of PAHs in food is due to environmental contamination, technological processing and from contaminated packaging material. Since they have been proven to present carcinogenic and genotoxic effect, the rapid and reliable determination of these compounds in food is very important. Solid-phase microextraction is an easy preparation technique, which allows to minimize solvent consumption and reduce sample manipulation. A Carbopack Z/ polydimethylsiloxane fiber, particularly suitable for extraction of planar compounds, was employed to extract PAHs. The analysis was performed by gas chromatography (GC) coupled to a fast quadrupole mass spectrometer (qMS). The method was first developed by direct immersion of the fiber in a diluted oil sample in hexane. Although very good results were obtained in terms of repeatability, accuracy, limit of detection, and limit of quantification, the method was never routinely applied since required frequent ion source cleaning and shortened the column life. Therefore a preliminary purification step was added to eliminate most of the triglycerides before the immersion of the fiber into the hexane solution. A rapid extraction of PAHs from oil was performed using a low amount of acetonitrile, then the compounds were back-extracted in hexane. Despite the non-quantitative extraction of polycyclic aromatic hydrocarbons from oil using acetonitrile, the signal-to-noise ratio was significantly improved obtaining a limit of detection largely below the performance criteria required by the European Union legislation.