Relative retention times of molecular species of acylglycerols, phosphatidylcholines, and phosphatidylethanolamines containing ricinoleate in reversed-phase HPLC

The relative retention times (RRT) of twenty one molecular species of diacylglycerols (DAG), forty two molecular species of triacylglycerols (TAG), thirty six molecular species of phosphatidylcholines (PC), and thirty six molecular species phosphatidylethanolamines (PE) in reversed-phase HPLC are reported. They were derived from incorporation of six [C-14]-labeled fatty acids, ricinoleate (R); stearate (S), oleate (O), linoleate (L), linolenate (Ln), and palmitate (P) in castor microsomal incubations. Most of these RRT were not reported earlier because the standards were not available, including the molecular species containing R. In general, DAG eluted earlier than TAG on a C-18 HPLC used for the separation of the molecular species of acylglycerols (AG). When only one acyl chain differed in the molecular species of both DAG and TAG, the elution order was: R, Ln, L, P, O, and S. Two C-8 HPLC systems were used for separation of the molecular species of PC and PE, respectively, with a more polar eluent used to elute the less polar PE. The elution order for the molecular species of both PC and PE, when one acyl chain was different, was the same as that of AG. The pairs of positional isomers of the molecular species of AG, PC, and PE elute closely. The RRT and elution characteristics reported are useful for the preliminary identification of molecular species of AG, PC, and PE, the important lipid classes in oil biosynthesis and membrane formation.