Submitted to: Journal of Chromatography
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/6/1996
Publication Date: N/A
Interpretive Summary: New analytical methods are needed for the rapid separation of mono- and diglyceride fatty acid isomers which differ only in the location of the fats in the molecular to understand physical and functional properties of lipid containing food products. We have developed a procedure which allows rapid determination of purity of glyceride synthesized in the laboratory and can also be used as a tool to isolate and/or study the structure of fats found in human systems. The procedure can also be used by the confectionery, chocolate and specialty fat industries to determine the exact structure(s) of their glycerides, an important consideration in crystallization, mouth feel and visual appeal.
Technical Abstract: Mono- and diacylglycerol positional isomer pairs were separated (as acetates) by silver ion high performance liquid chromatography on a commercially available column using an isocratic solvent system of 1.2% (v:v) acetonitrile in hexane and flame ionization detection. Preparation of the acetate derivative(s) from the 1- and 2-monoacylglycerols and 1,2- and 1,3-diacylglycerols (acetic anhydride/ pyridine) results in <3% isomerization in the thermodynamically less stable 2-mono- and 1,2- diacylglycerols (to the 1(3)-mono and 1,3-diacylglycerols, respectively), <1% in the 1- and 1,3- analogues. The triacylglycerol, the diacylglycerol/ monoacetate isomer pair, the monoacylglycerol/ diacetate isomer pair and triacetin were completely separated for the 16:0 and 18:1 fatty acid series. The TAG eluted first; the triacetin eluted last. The 16:0 elution pattern is unusual, since silver ion chromatographic separations are generally ascribed to the interaction of silver ions with double bond pi- electrons, a condition absent in the 16:0 series.