Positional isomerism of unsaturated fatty acids in the rat quantification of isomeric mixtures

Abstract

Abstract Mono‐ and dienoic acids of lipids from rat milk, rat sucklings, and rats on a fat‐deficient diet were investigated. The percentage of uncommon isomers of palmitoleic acid was highest in milk, the newborn and the suckling rats, but receded after weaning. Isomers of linoleic acid were found only in traces in sucklings but became pronounced in rats on diets lacking essential fatty acids. The proportion of 8,11‐diene among octadecadienoic acids increased markedly under such conditions within one week and two additional isomers became prominent after longer periods of fat‐deficient diet. A supplement of hydrogenated coconut fat did not influence the occurrence of these isomers. Dietary petroselinic acid is incorporated by the rat into tissue lipids. 4‐Hexadecenoic and a small amt of 8‐eicosenoic acid arise from it. Quantification of isomeric mixtures by ozonization‐hydrogenation and subsequent gas‐liquid chromatography is discussed in detail.