title: Comparison of different methylation methods for the analysis of conjugated linoleic acid isomers by silver ion HPLC in beef lipids.
abstract: Four different methods for the methylation of conjugated linoleic acid isomers (CLA) in ruminant lipids were compared by silver ion (Ag+) HPLC. The combination of base-catalyzed methods followed by an acid-catalyzed method with BF3/MeOH was tested under different temperatures (room temperature and at 60 degrees C), along with based-catalyzed methylation with NaOCH3 and methylation with BF3/MeOH after saponification with NaOH. The comparison among these four methods was done on muscle and adipose tissue samples from bulls. The repeatability theta of the combined base- and acid-catalyzed methylation (NaOCH3/BF3) at ambient temperature for 20 min and at 60 degrees C for 10 min was most suitable for the quantitative Ag+-HPLC analysis of CLA isomers. At 60 degrees C the combined methods supplied the highest concentrations of most CLA isomers. The base-catalyzed methylation and the saponification followed by BF3/MeOH methylation for 5 min generated significantly lower concentrations for most CLA isomers compared to the combined methods.
authors.affiliation: Department of Muscle Biology and Growth, Research Institute for the Biology of Farm Animals, Wilhelm-Stahl-Allee 2, D-18196 Dummerstorf, Germany. gnuernbg@fbn-dummerstorf.de
authors.forename: Karin
authors.initials: K
authors.lastname: Nuernberg
authors.forename: Dirk
authors.initials: D
authors.lastname: Dannenberger
authors.forename: Klaus
authors.initials: K
authors.lastname: Ender
authors.forename: Gerd
authors.initials: G
authors.lastname: Nuernberg
mesh_terms: D000273:Adipose Tissue / Q000737:chemistry; D000818:Animals; D002412:Cations; D002417:Cattle; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D044243:Linoleic Acids, Conjugated / Q000032:analysis*; D008055:Lipids / Q000032:analysis*; D008297:Male; D008460:Meat / Q000032:analysis*; D008745:Methylation; D018482:Muscle, Skeletal / Q000737:chemistry; D012834:Silver
chemical_list: D002412:Cations; D044243:Linoleic Acids, Conjugated; D008055:Lipids; D012834:Silver