Octanoic acid (OA) is an ingredient of peracetic acid-based sanitizers (PAS), which are widely used in the sanitation of uncooked food. Since, OA can remain on PAS-treated foods, we developed a simple analytical method to determine OA levels in uncooked foods. The developed method involves straightforward solvent extraction with diethyl ether, derivatization with sulfuric acid/ methanol and gas chromatography coupled with mass spectrometry. The recovery and relative standard deviation of OA ranged from 74.2 to 96.6% and 2.6 to 9.6%, respectively. The limit of quantification (LOQ) in foods was estimated to be 0.02 mg/kg. We applied the developed method to imported uncooked foods (56 beef samples, 34 vegetable samples and 89 fruit samples), and found that OA levels ranged from 0.34 to 0.53 mg/kg, the LOQ to 0.48 mg/kg and LOQ to 1.12 mg/kg, respectively. Most of the determined OA in imported uncooked foods could be considered to be derived from OA naturally contained in the foods.
