title: Separation behavior of octadecadienoic acid isomers and identification of cis- and trans-isomers using gas chromatography.
abstract: Using a strongly polar cyanopropyl capillary column we have investigated the gas chromatography (GC) separation behaviors of 24 octadecadienoic acid methyl ester (18:2ME) isomers compared against saturated methyl stearate (18:0ME) and arachidic acid methyl ester (20:0ME), and the dependency on the GC column temperature. The 24 isomers were obtained by performing cis-to trans-isomerization of six regioisomers: five of the 18:2ME isomers were prepared by the partial reduction of methyl α-linolenate and methyl γ-linolenate C18 trienoic acids with different double bond positions, whereas the sixth isomer, 18:2ME (c5, c9), was obtained from a raw constituent fatty acid methyl ester (FAME) sample extracted from Japanese yew seeds. There are no reference standards commercially available for 18:2ME isomers, and in elucidating the elution order of these isomers this study should help the future identification of cis- and trans-type of 18:2ME. We also report the identification method of cis- and trans-type of FAME using equivalent chain lengths and attempt the identification of cis- and trans-type of 18:2ME isomers from partially hydrogenated canola oil.
authors.affiliation: Shimadzu Corporation, 3-9-4, Hikaridai, Seika-cho, Soraku-gun, Kyoto, 619-0237, Japan, sibamoto@shimadzu.co.jp.
authors.forename: Shigeaki
authors.initials: S
authors.lastname: Shibamoto
authors.forename: Andrew
authors.initials: A
authors.lastname: Gooley
authors.forename: Kouhei
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D002849:Chromatography, Gas / Q000379:methods; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004952:Esters; D005231:Fatty Acids, Unsaturated / Q000737:chemistry / Q000302:isolation & purification*; D007536:Isomerism; D008745:Methylation
chemical_list: D004952:Esters; D005231:Fatty Acids, Unsaturated; C027369:octadecadienoic acid