Gas chromatographic separations of di- and monoacylglycerols based on the degree of unsaturation and positional placement of acyl groups

Abstract

Gas liquid chromatographic analysis of diacylglycerols (DGs) and monoacylglycrols (MGs) prepared by Grignard degradation of the triacylglycerols of plant and fish oils was examined as acetate and trimethylsilyl (TMS) ether derivatives on several polar cyanosiloxanes. Satisfactory separations of mixtures of DGs or MGs from simple plant oils based on carbon number and degree of unsaturation, as either acetates or TMS ethers, were obtained on SILAR 10C. In addition, the TMS ethers were effectively separated on the basis of the positional distribution of fatty acid in the acylglycerol molecule, but the acetates of the positional isomers overlapped. The equivalent chain lengths (ECLs) of DGs with 28–42 total acyl carbons and 0–6 double bonds, and MGs with 14–22 acyl carbons and 0–6 double bonds, are presented for both derivatives. The influence of column temperature on the ECLs is discussed.