Determination of Triacylglycerol Composition of Trichilia emetica Seed Oil using GC-MS and 1H-NMR Spectroscopy

Abstract

Trichilia emetica seed oil was analysed for their fatty acid profiles using GC-MS and ¹H-nuclear magnetic resonance spectroscopy (¹H-NMR). In the ¹H-NMR spectrum, integrating the values of the signals of acyl, allylic and bis-allylic protons, the unsaturated fatty acid: monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) was quantitated. The relative percentage of saturated fatty acid (SFA) was determined by subtracting the relative amount of the total unsaturation from the total amount of fatty acid present in the oil. The procedure was verified by using GC-MS to determine the fatty acid methyl esters in the oil sample. The percentage triacylglycerol conversion to its corresponding methyl esters was determine by ¹H NMR and was calculated to be 94%. A total of six FAMEs were identified in the seed oil by the NIST library match software and the fragmentation pattern data of GC/MS. The results obtained from the two methods were 55 % saturated (C14:0, C16:0, C18:0), 35% monounsaturated (C18:1) and 10 % polyunsaturated (C18:2 and C18:3). Generally, the ¹H-NMR results were in good agreement with gas chromatographic (GC) analyses. In conclusion, the ¹H-NMR-based procedures is fast as it does not require the oil to be derivatized and can be applied to neat T. emetica seed oil.