A comparison of structural–functional equation models to identify fatty acids on three common gas chromatography columns

Abstract

Reported herein is a series of new structural–functional relationship equations which provide relevant structural information of unknown fatty acid methyl esters (double-bonds, chain-length, and omega-bond position) based upon temperature induced shifts in equivalent chain length's (ECLs). The induced ECL changes were accomplished upon two cyanoalkyl (Supelco SP-2560, fast GC; Varian Factor 4, VF-23) and one stabilised PEG column (Innowax). Regression on this data-set permitted the development of classical linear equations. To calculate the ECL values, bracketing saturated fatty acid methyl esters (FAMEs) were run in the same admixture as the unsaturated FAMEs. The equations developed for each of the three columns are demonstrated to have varying capacity to accurately identify the chain-length, double-bond number and omega-bond position.