COINCIDENCE OF CIS-MONOETHYLENIC AND TRANS-MONOETHYLENIC FATTY-ACIDS SIMPLIFIES THE OPEN-TUBULAR GAS-LIQUID-CHROMATOGRAPHY OF BUTYL ESTERS OF BUTTER FATTY-ACIDS

Fatty acids of whole butterfat were converted to butyl esters and fractionated by thin-layer chromatography on silica gel impregnated with AgNO3. Fractions of C-10-C-18 fatty acids were examined on a bonded polyglycol open-tubular gas-liquid chromatography (GLC) column. Comparisons of fractions showed that butyl esters of cis and trans monoethylenic fatty acids coincided exactly for most bond positions. Polyglycol column GLC of butyl esters thus simplifies analysis of butterfat. Some monoethylenic acids with bond positions closer to the carboxyl group than major components such as cis-18:ln-9 did not resolve from these components. A trans-18:ln-3 fatty acid previously reported was not found, but trans-18:ln-6, n-5, n-4 and n-2 were confirmed from GLC properties. The fatty acids 12:1 and 14:1 were shown by TLC and GLC to be exclusively a single cis isomer with the ethylenic bond in the Delta 9,10 position. The GLC evidence for the unusual vinyl bond in the 10:ln-1 of butterfats is reviewed. It is proposed that these three fatty acids are products of a desaturase through the animal biochemistry proper as distinct from the rumen biochemistry processes which lead to the multiplicity of isomers of 16:1 and 18:1 fatty acids.