Determination of double bond positions in polyunsaturated fatty acids using combination gas chromatography - mass spectrometry

✍ Scribed by Walter G. Niehaus Jr.; Ragnar Ryhage

• Publisher: Elsevier Science
• Year: 1967
• Tongue: French
• Weight: 326 KB
• Volume: 8
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)89960-3

✦ Synopsis

The determination of the positions of ethylenic bonds in multiply unsaturated acyclic compounds is a formidable problem. Classical approaches have involved oxidative cleavage of the double bonds, followed by characterization of the fragments produced, ueually by ga.a chromatography. The use of mass spectrometry for determination of double bond position has not thus far yielded much useful information. Compounds ieomeric with respect to double bond positions give very similar or identical spectra (1). A number of derivative8 of unsaturated fatty acids have been prepared and studied by mass spectrometry. Catalytic deuteration of the double bonds is not satisfactory due to extensive incorporation and exchange of deuterium (2). Reduction with deuterio -hydrazine gives somewhat more satisfactory results (3). but is complicated by hydrogen-deuterium exchange reactions (4). and by rearrangements during the electronic bombardment (5). Epoxidation of a monoenoic acid

TABLE 1 Principal Ion Fragments d -Linolenic Acid Derivative Per cent Double of base bond peti position 201