Gas-liquid chromatography-mass spectrometry of the 4,4-dimethyloxazoline derivatives of Δ5-unsaturated polymethylene-interrupted fatty acids from conifer seed oils |
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Authors: | Olivier Berdeaux Robert L. Wolff |
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Affiliation: | (1) INRA, Unité de Nutrition Lipidique, Dijon;(2) ISTAB, Laboratoire de Lipochimie Alimentaire, Université de Bordeaux 1, Allée des Facultés, 33405 Talence Cedex, France |
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Abstract: | The fatty acids from the seed oils of three Conifer species (one Pinaceae,Pinus pinaster, and two Cupressaceae,Chamaecyparis lawsoniana andBiota orientalis) have been analyzed as their 4,4-dimethyloxazoline (DMOX) derivatives by gas-liquid chromatography coupled with mass spectrometry. The structures of six Δ5-unsaturated polymethylene-interrupted fatty acids (Δ5-UPIFA) were established, confirming previous studies in which they were identified by their equivalent chainlengths (ECL) and by comparison with related authentic standards. These acids were:cis-5,cis-9 18∶2,cis-5,cis-9,cis-12 18∶3 (P. pinaster),cis-5,cis-9,cis-12,cis-15 18∶4 (C.lawsoniana),cis-5,cis-11 20∶2,cis-5,cis-11,cis-14 20∶3 (all species),cis-5,cis-11,cis-14,cis-17 20∶4 (B. orientalis) acids. In addition,cis-9 18∶1,cis-9,cis-12 18∶2 (all species) andcis-9,cis-12,cis-15 18∶3 (Cupressaceae) acids, together with their elongation products [cis-11 20∶1,cis-11,cis-14 20∶2 (all species) andcis-11,cis-14,cis-17 20∶3 (B. orientalis) acids] were also identified. In the mass spectra, DMOX derivatives of all Δ5-UPIFA showed an intense peak atm/z 153, which is a diagnostic ion of fatty acid derivatives with a Δ5-ethylenic bond. Other double bonds were localized by ion pairs that differed by 12 atomic mass units. The present study fully justifies the use of ECL to identify Δ5-UPIFA in Conifer seed oils, in which they are ordinary components. |
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Keywords: | Conifer seed oil Δ 5-ethylenic bond 4,4-dimethyloxazoline derivatives equivalent chainlengths gas-liquid chromatography mass spectrometry |
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