Rapid identification of γ-irradiated food by direct solvent extraction and liquid chromatography-tandem mass spectrometric analysis of 2-dodecylcyclobutanone: Application in surveillance of irradiated food

2-Dodecylcyclobutanone (2-DCB) is one of the major 2-alkylcyclobutanones (2-ACBs) that are uniquely formed when triglycerides are exposed to ionizing radiation and is being widely used as marker signature for identifying irradiated food. Current methods for 2-DCB extraction are either time-/solvent-consuming or involve the use of expensive extraction instruments. We have developed in this study an efficient extraction method for extracting 2-DCB from γ-irradiated food by direct extraction using acetonitrile. In comparison with the European standard method for irradiated food identification, our method reduced the per sample organic solvent consumption from 450 to 30 mL per sample and shortened sample processing time from 8 h to 30 min. The assay combining direct acetonitrile extraction, precolumn derivatization with hydroxylamine, and LC-MS/MS analysis was validated with irradiated chicken as positive control, and applied in surveillance of irradiated food in Hong Kong.