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RESEARCH PRODUCT

Enantiomer separation by chiral-phase liquid chromatography of urethane derivatives of natural diacylglycerols previously fractionated by reversed-phase liquid chromatography

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Abstract Enantiomers of diacylglycerols such as 3,5-dinitrophenyl isocyanate (urethane) derivatives previously fractionated by reversed-phase high-performance liquid chromatography (HPLC) were separated by HPLC on a chiral phase column [N-( R )-1-(α-naphthyl)ethylamino-carbonyl-( S )-valine chemically bound to γ-aminopropylsilanized silica]. In addition to the separation of commercial monoacid-diacylglycerol isomers, separation of diacid-diacylglycerol isomers obtained from peanut oil and cottonseed oil triacylglycerols by chemical hydrolysis is reported. Hexane-ethylene dichloride-ethanol mixtures were used for elution of the diacylglycerol derivative isomers, which were detected by their refractive indices or their UV absorption. The sn -1,2- and sn -2,3-isomers of a racemic mixture were well separated whereas the sn -1,3- and sn -1,2-isomers were eluted together. In complex mixtures the elution order varies as a function of chain length and unsaturation of the constituent fatty acids, additionally to their positioning. The enantiomer compositions of mixtures calculated from peak areas are similar in both types of detection and are assumed to be representative. The method can be applied to compositional analysis of diacylglycerol optical isomers during studies of the stereospecific distribution of fatty acids in natural triacylglycerols.