Comparison of fatty acid methyl esters of palm and palmist oils determined by GCxGC–ToF–MS and GC–MS/FID

Abstract

Palm oil obtained from the mesocarp of Elaeis guineensis contains polyunsaturated fatty acids which are essential for normal human growth and development. Five samples of palm oil obtained from Cameroon (n=3), Nigeria (n=1) and Ghana (n=1) and two palmist oil samples (commercially available and raw oils) were obtained from Cameroon. Comprehensive gas chromatography coupled to time of flight mass spectrometry (GCxGC–ToF–MS) and gas chromatography coupled to mass spectrometry and/or a flame ionization detector (GC–MS/FID) were used to determine the fatty acids, as their methyl esters (FAMEs) in these two products. The major compounds as determined with GCxGC–ToF–MS and GC–MS/FID in palm oil were hexadecanoic acid methyl ester (27.4–44.1%), 9-octadecenoic acid methyl ester (33.7–45.2%), 9–12-octadecadienoic acid methyl ester (8.5–13.4%) and stearic acid methyl ester (2.7–13.7%). Some of the minor FAMEs were region specific. The palmist oil showed little variation (both with one and two dimensional GC) with dodecanoic acid methyl ester (30.4–40.1%), tetradecanoic acid methyl ester (15.1–20.6%), (9-octadecenoic acid methyl (13.0–17.6%) and hexadecanoic acid methyl ester (11.2–18.4%), being the most prominent. Identified FAMEs such as (Z,Z,Z)-9,12,15-octadecadienoic acid methyl ester; tetradecanoic acid, 12-methyl, methyl ester were used to differentiate between the two palmist oils when using two dimensional GC. In general fewer FAMEs could be detected by GC–MS/FID (usually less than 10), while this number doubled when the oils were separated using two dimensional GC.