The structural characterization of molecular species in fish oil, a complex mixture of various compounds, was carried out by high performance liquid chromatography/fast atom bombardment mass spectrometry (HPLC/FAB-MS) with a FRIT-FAB interface. Mass chromatograms and mass spectra obtained by HPLC/FAB-MS provided indication of the possible combinations of fatty acid in each triacylglycerol component in fish oil. In this manner, the compositions of polar and labile fractions comprised of polyunsaturated fatty acids such as icosapentaenoic acid and docosahexaenoic acid, were determined. This determination is difficult with GC/MS or HPLC. Differences in molecular species in fish oil and fractionated fish oil at -60°C were also examined by the present methode.
