Some monomethyl‐branched fatty acids from ruminant fats: Open‐tubular GLC separations and indications of substitution on even‐numbered carbon

Abstract

Isomeric methyl esters of fatty acids in three groups (C15, C17, C19) have been isolated from ruminant fats. Basic structural analysis by physiochemical techniques indicated that these odd-numbered fatty acids were even chain with a single methyl branch on the chain. High resolution open-tubular gas liquid chromatographic studies indicate that, with the exception of iso acid impurities in these fractions, only even-numbered carbons of the fatty acid chains bear the methyl branch.

Composition and variability of the branched‐chain fatty acid fraction in the milk of goats and cows

“…Exclusively even carbon methylsubstitutions were found by Ackman et al (7) in the Cls and C17 fraction of butterfat. In all these studies, the separation of the methyl esters was achieved on high resolution capillary gas chromatography (GC) columns with (5,7) or without (6) enrichment of the branchedchain fatty acid fraction. Strocchi and Holman (8) confirmed the presence of iso-and anteisofatty acids in butterfat with other monomethylbranched fatty acids being absent.…”

“…Monomethyl-branched fatty acids with methyl-substitution on even-and odd-numbered carbon atoms are reported in milk fat of these species (5,6). Exclusively even carbon methylsubstitutions were found by Ackman et al (7) in the Cls and C17 fraction of butterfat. In all these studies, the separation of the methyl esters was achieved on high resolution capillary gas chromatography (GC) columns with (5,7) or without (6) enrichment of the branchedchain fatty acid fraction.…”

Selection of internal standards for determining quantitative recovery of isoprenoid acids after urea complexing

“…The natural occurrence in certain lipids of 11-cyclohexylundecanoic acid (13,(21)(22)(23) suggested another class of compounds suitable for analyses of materials resistant to urea complexing. We prepared both decyl and nonyl esters of 3-cyclohexylpropionic acid for investigation.…”

“…The other data given in Table II shows, through the effect of different conditions and polarities of columns on retention times for the more polar liquid phases such as DEGS and SILAR-7CP and the two esters, that esters of 3-cyclohexylpropionic acid are not strictly apolar, thus offering some flexibility in choice of GLC operating conditions. The data offer a guide to the choice of aliphatic ester materials for inclusion in mixtures such as the isoprenoid acids or monomethyl-branched aliphatic esters (21,25,26) where one might be inconvenient due to coincidence with a known compound such as methyl l l-cyclohexylundecanoic acid or methyl 9-cyclohexylnonanoic acid (13).…”

The nonpolar egg wax lipids of the cattle tick,Boophilus microplus (Canestrini)

“…However, medium chain length acids with methyl branches in any of the 8-, 10-, or 12positions occur frequently in nature. They are generated as a waterproofing agent by the preen glands of the swan, Cygnus olor (19), and are found in dairy products (20) and ruminant tissue (21). The esterifying C26 and C28 alcohols are common in hair lipids (22) and wool wax (23) and would seem to be general superficial lipoid material.…”