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Geometrical isomerisation of eicosapentaenoic and docosahexaenoic acid at high temperatures
Author(s) -
Mjøs Svein A.,
Solvang Marianne
Publication year - 2006
Publication title -
european journal of lipid science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.614
H-Index - 94
eISSN - 1438-9312
pISSN - 1438-7697
DOI - 10.1002/ejlt.200600055
Subject(s) - isomerization , docosahexaenoic acid , double bond , chemistry , eicosapentaenoic acid , cis–trans isomerism , reaction rate constant , structural isomer , linoleic acid , arrhenius equation , polyunsaturated fatty acid , fatty acid , medicinal chemistry , chromatography , analytical chemistry (journal) , organic chemistry , activation energy , kinetics , catalysis , physics , quantum mechanics
Concentrates of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were heated at 140–240 °C for 2–8 h under nitrogen. The trans isomers were analysed by gas chromatography‐mass spectrometry on a BPX‐70 cyanopropyl column. All geometrical isomers of EPA and DHA with one trans double bond were observed. The rate constants ( k ) for the isomerisation of the all‐ cis isomers were calculated and found to be higher than previously reported for linoleic acid and α‐linolenic acid. Arrhenius plots showed a linear relationship between ln k and the reciprocal absolute temperature above 180 °C. The distribution patterns of isomers with one trans double bond are approximately constant up to a degree of isomerisation of 25%. The degree of isomerisation can therefore be estimated from selected trans peaks.
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