Silver ion chromatography and gas chromatography-mass spectrometry in the structural analysis of cyclic dienoic acids formed in frying oils

✍ Scribed by Gary Dobson; William W. Christie; Elizabeth Y. Brechany; Jean Louis Sebedio; Jean Luc Le Quere

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 855 KB
• Volume: 75
• Category: Article
• ISSN: 0009-3084
• DOI: 10.1016/0009-3084(95)02420-n

✦ Synopsis

Sixteen cyclic dienoic fatty acids formed from linolenic acid in linseed oil heated to 275°C were characterised after fractionation by silver ion high-performance liquid chromatography and analysis by gas chromatography-mass spectrometry of the picolinyl esters and dimethyloxazoline derivatives, before and after hydrogenation and deuteration. The stereochemistry of the double bonds were elucidated by gas chromatography-Fourier transform infrared spectroscopy. Rings of eight cyclopentenyl fatty acids (51% of the total cyclic dienes) were formed from C10 to C14 (22%) and C I ! to CI 5 (29%) of the original chain with the double bonds (C12 and C15, and C9 and C 12, respectively) remaining in their original positions. Rings of eight cyclohexenyl fatty acids (49%) were formed from C10 and C15 of the original chain with double bonds at either C8 and C12 (26%) or Ci2 and C16 (23%). All possible combinations of configurational isomers of both the cyclopentenyl/cyclohexenyl ring and the double bond in the straight chain were formed. For the cyclopentenyl fatty acids there were similar amounts of Z and E double bond isomers and a predominance of trans ring isomers. For the cyclohexenyl fatty acids there was a predominance of E double bond isomers and similar amounts of both ring isomers.