Supercritical fluid extraction of hydrocarbons and 2-alkylcyclobutanones for the detection of irradiated foodstuffs

Supercritical carbon dioxide can be used to carry out a selective and fast extraction (30 min) of volatile hydrocarbons and 2-alkylcyclobutanones contained in irradiated foods. After elimination of the traces of triglycerides still contained in the extracts on a silica column, the compounds were analysed by gas chromatography–mass spectroscopy (2-alkylcyclobutanones) and gas chromatography-flame ionization detection (volatile hydrocarbons). The present method was applied successfully to freeze-dried samples (1 g or less) of cheese, chicken, avocados and to various ingredients (chocolate, liquid whole eggs) included in non-irradiated cookies. It was faster (4–5 h) than the reference methods EN 1784 (volatile hydrocarbons) and EN 1785 (2-alkylcyclobutanones), which take 1.5 days each. The minimal dose detectable by this method is, in addition, slightly lower than those of the reference methods.