Chiral-phase HPLC resolution of enantiomeric diacylglycerol moieties of fish-oil triacylglycerols

The HPLC resolution of the enantiomeric sn-1,2- and sn-2,3-diacylglycerol ( DG) moieties of fish-oil triacylglycerols (TGs) having different fatty acid compositions was carried out on a chiral stationary phase, (R)-1-(l-naphth yl)ethylamine. The DGs were generated from TGs of tuna orbital, pomfret fle sh and pacific saury flesh by partial Grignard degradation; they were chrom atographed as 3,5-dinitrophenylurethanes. By an isocratic elution with n-he xane-1,2-dichloroethane-ethanol 40 : 30 : 1 (v/v/v) as the mobile phase, th e sn-1,2(2,3)-DGs from tuna orbital and pomfret flesh were resolved into tw o clearly distinguishable enantiomer groups, although some peak overlapping s between the enantiomers were observed in the latter sample. On the other hand, no clear enatiomer resolution was obtained for the saury flesh DGs. T he poorer resolution was mainly caused by the existence of large amounts of long-chain monounsaturated fatty acids (20 : I and 22 : I) in the molecule s.