Effect of temperature on the separation of the esters of fatty acids by open tubular gas chromatography

Abstract

The effect of temperature on the separation of the methyl esters of fatty acids by open tubular gas chromatography on Apiezon L, butane-1, 4-diolsuccinate (BDS) and diethylene glycol succinate (DEGS) was studied. For the separation of the methyl esters of fatty acids, the determination of the effect of temperature on the variations of the equivalent carbon chain length ( ECL) was found to be a convenient method. The values of the ECL were determined with a reproductibility of better than ±0.01 carbon atom. The possible errors of measurements of ECL values are discussed. The ECL values of the methyl esters of branched fatty acids found on Apiezon L and BDS are practically independent of temperature, whereas on DEGS temperature has a definite effect. The ECL values of the methyl esters of unsaturated fatty acids found on Apiezon L as well as on the polyester phases (BDS, DEGS) increase with temperature. The slope of δ ECL/δ t increases with the increase in the number of double bonds in the molecule and with the polarity of the stationary phase. For stereoisomers, the values of δ ECL/δ t are higher for the methyl esters of acids that have a cis configuration.