Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/1996
Publication Date: N/A
Technical Abstract: During development of a silver ion HPLC method to determine the structural integrity of synthesized monoacyl (MAG) and diacylglycerols (DAG), the retention characteristics of fatty acid methyl esters (FAME) and triacylglycerols (TAG) were found to be influenced not only by the number and/or configuration of the double bonds in the molecules, but also by the number of carbon atoms in the fatty acid (FA) chains. A mixture of 16:0 MAG, DAG and TAG (in which the MAG and DAG have been converted to the di- and monoacetates, respectively) was readily separated utilizing a system of two Chrompack Chromspher 5 Lipids (TM) columns connected in series, a solvent system of 1.2% acetonitrile in hexane, and flame ionization detection. Silver ion chromatographic separations are generally attributed to the interaction of silver ions with double bond pi-electrons, a condition absent in the 16.0 series. Mixtures of 6- to 18-carbon FAME and 8- to 54-carbon TAG were also analyzed and increasing retention with shorter FA chain length was again observed. A similar phenomenon has been noted in the separation of MAG and DAG (as acetates) by thin layer chromatography on silica gel G plates. Thus, substrate interactions with the more polar silica backbone of the AG-HPLC column packing (some 30% of the original hydroxy groups of the silica remain unreacted) may contribute to the observed differences in retention.