Determination of 2-alkylcyclobutanone using fluorescent labelling

2-Alkylcyclobutanones are formed under the influence of ionising radiation from triglycerides. The determination of cyclobutaneones could be a powerful means of identifying irradiated foods, not only from a legal viewpoint but also in food quality control. In this paper 2-dodecylcyclobutaneone was used as a model substance, synthesised by means of the key substance 1-bromo-1-ethoxycyclopropane. The determination was carried out by labelling the cyclic ketone with fluorescent dyes and subsequent HPLC separation. 1-Pyrenebutyrylhydrazide and 7-diethylamino-3-carbonylazide were used as labelling reagents. Dodecylcyclobutanone was sensitively determined in fat matrices. Labelling with 1-pyrenebutyrylhydrazide was unsuccessful because of its low reactivity. Medium- and short-chain aldehydes and ketones were easily labelled. After reduction to the corresponding alcohol, dodecylcyclobutanone, as well as aldehydes and ketones, were successfully labelled with 7-diethylamino-3-carbonylazide. Separation was carried out with good results on RP-18 reversed phases using methanol water mixtures as mobile phases. The detection limit of dodecylcyclobutanone is about 5 ng. Present address: Institut für Lebensmittelchemie, Technische Universität Berlin, Gustav-Meyer-Allee 25, D-13355 Berlin, Germany