Identification of Fatty Acid Methyl Esters as Minor Components of Fish Oil by Multidimensional GC/MSD: New Furan Fatty Acids


App Note 3/1993

The separation and analysis of very low concentrated furan fatty acids and other minor component fatty acids in complex sample matrices, such as fish oil or lipids derived from liver and testes, require several pre-analytical separation steps in order to obtain sufficient resolution in single column gas chromatography: after extraction and transesterification hydrogenation, urea complex precipitation and Ag+-TLC were applied prior to GC-analysis of furan fatty acids. By using a multidimensional GC/MSD-System with cooled injection and flow controlled column switching with cold trapping in between, it is now possible to identify directly the methyl esters of furan fatty acids without any further pre-analytical separations. The most common of the furan fatty acids can be subdivided into two groups, bearing either a propyl or a pentyl side chain in the 5-position of the furan ring. In addition to the known eight furan fatty acids in fish oil, six new ones were identified, four with a propyl and two with a pentyl side chain. Four of them were reported earlier to be found in the hepatopancreas of crayfish and in fish tissue, whereas the propyl group 16,19-epoxy-17,18-dimethyldocosa-16,18-dienoic acid and the pentyl group furan fatty acid 6,9-epoxy-7-methyltetradeca-6,8-dienoic acid are hitherto unknown ones.