Separation of Enantiomeric Triacylglycerols by Chiral‐Phase HPLC

Abstract

Liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC-MS/APCI) with a chiral phase was used for separation of triacylglycerols (TAG) obtained either by organic synthesis or isolated from different algal species. We present chromatographic characteristics and tandem mass spectra of enantiomers and positional isomers (regioisomers) of C16, C18 and C20 polyunsaturated fatty acids. The retention time was found to depend on the structure of the given TAG, increasing with increasing number of double bonds and decreasing with increasing number of the carbons in TAG, with the exception of dieicosapentaenoyl-palmitoyl-glycerols.

Separation and Identification of Odd Chain Triacylglycerols of the Protozoan Khawkinea quartana and the Mold Mortierella alpina Using LC–MS

“…The LC system used for separation in the chiral mode was the same as previously described [28]. Briefly, the Astec cyclobond™ I 2000 DMP (3,5-dimethyl-phenyl-carbamate modified β-cyclodextrin) chiral LC column was used.…”

“…2. Based on previously published work [28,30], we again used the column packed with chiral oligosaccharide, i.e., β-cyclodextrin modified by tris-3,5-dimethylphenylcarbamate. TAG retention time then depends on the number of double bonds in fatty acids bound to the glycerol backbone.…”

“…If the TAG is composed of three different fatty acids, then it may be composed of up to six molecular species. Their identification essentially depends on the availability of standards (individual enantiomers), which cannot always be separated from each other [18,28], so we did not deal with this issue here.…”

The Updated Bottom Up Solution Applied to Atmospheric Pressure Photoionization and Electrospray Ionization Mass Spectrometry

“…linoleic acid, L) or triunsaturated (e.g. linolenic acid, Ln) FA in the sn-1 and sn-3 positions were not separated, such as LPP/PPL, LOP/ POL, LLP/PLL, AALn/LnAA, LnOA/AOLn and LnLnA/ ALnLn [16], while in other cases enantiomers such as LLP/ PLL were separated [18]. Still, even when separated using CC, the mass spectra showed negligible or no differences between enantiomers.…”

“…Similarly, in Type III TAG, although the FA in the sn-2 position can be identified, ABC cannot be distinguished from its enantiomer CBA. Enantiomers can only be differentiated using chiral chromatography (CC) [15][16][17][18]. Even so, not all isomers may be separable using CC, depending on the column and conditions used.…”