Rapid Gas Chromatographic Screening of Vegetable Oils for Free Fatty Acids

A rapid gas chromatographic profiling method for the simultaneous analysis of free fatty and other acids was applied to vegetable oils. Oil samples were dissolved in dichloromethane and the free acids were extracted with saturated solution. The aqueous extract was acidified and then loaded onto the Chromosorb P column for the extraction. The acids were eluted with diethyl ether selectively from Chromosorb P column and were treated with triethylamine to prevent the losses of volatile acids. Several long chain fatty acids were detected from soybean oil, rice-bran oil, sesame oil and perilla oil. Various organic acids including odd number fatty acids were detected in crude oil, especially sesame oil. Arachidic acid from perilla oil and vanillic acid from sesame oil, which were not reported before were detected. The content ratio of free linoleic acid to oleic acid was , which was similar to the reported data. When the GC profile of organic acids were simplified to their corresponding retention index spectra of bar graphical forms, they presented characteristic pattern of each vegetable oil that can be quickly recognized.