Identification of Hogwash Oil by Headspace GC/MS

The volatile components of hogwash oil samples were analyzed by static headspace and gas chromatography-mass spectrometry(Hs／GC-MS)．The second grade production of the deteriorated oil, hexanal were identified in oil for frying. By comparing hogwash oil and the normal edible oils, the final grade production of the deteriorated oil fatty acid were identified in this experiment. So the discrimination components of the refined oil gained from the sewer and the normal edible oils were found, that was small molecular fatty acids．The butyric acid was the most important.