Determination of unsaturated fatty acid composition by high-resolution nuclear magnetic resonance spectroscopy

High-resolution nuclear magnetic resonance (NMR) spectroscopy provides useful data for analyzing fatty acid compositions of edible vegetable oils. Quantitation of each fatty acid was carried out by evaluation of particular peaks. According to the ¹H NMR method, terminal methyl protons, divinyl protons, and allyl protons are useful to calculate linolenic acid, linoleic acid, and oleic acid, respectively. The ω-2 carbon, divinyl carbon, and allylic carbons were used for calculation of these acids by the ¹³C NMR method. Compositional results obtained by NMR coincided well with those of the conventional gas chromatography (GC) method. Results from ¹³C NMR were in better agreement with those from GC than were the results obtained by the ¹H NMR method.