title: Re-characterization of three conjugated linolenic acid isomers by GC-MS and NMR.
abstract: Conjugated linolenic acids (CLN) refer to a group of octadecatrienoic acids with three conjugated double bonds. Minor positional and geometrical differences among CLN isomers make their separation and identification difficult. We have used GC-MS and NMR to study three common CLN isomers namely alpha-eleostearic acid, beta-eleostearic acid and punicic acid, finding that some signals of olefinic carbon atoms in NMR spectra were mistakenly assigned in the literature. The present study was therefore undertaken to re-characterize the location of CC double bonds and assign the chemical signals of proton and carbon atoms using (1)H NMR, (13)C NMR, (1)H-(1)H two-dimensional correlation spectra ((1)H-(1)H COSY) and (13)C-(1)H two-dimensional correlation spectra ((13)C-(1)H COSY). The geometrical structure of double bonds in these three CLN isomers was identified using homonuclear decoupling technique.
authors.affiliation: College of Chemistry & Chemical Engineering, Lanzhou University, Lanzhou, Gansu Province 730000, PR China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Cao
authors.forename: Lin
authors.initials: L
authors.lastname: Yang
authors.forename: Hong-Li
authors.initials: HL
authors.lastname: Gao
authors.forename: Jing-Nan
authors.initials: JN
authors.lastname: Chen
authors.forename: Zhen-Yu
authors.initials: ZY
authors.lastname: Chen
authors.forename: Qiu-Shi
authors.initials: QS
authors.lastname: Ren
mesh_terms: D008401:Gas Chromatography-Mass Spectrometry; D007536:Isomerism; D008042:Linolenic Acids / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy
chemical_list: D008042:Linolenic Acids; C004934:eleostearic acid; C519714:punicic acid