A quick method for routine analysis of C18 trans fatty acids in non-hydrogenated edible vegetable oils by gas chromatography-mass spectrometry

A quick routine analysis has been established for quantitative determination of thirteen individual C18 trans fatty acids in both pressed and solvent extracted non-hydrogenated edible vegetable oils, using gas chromatography-mass spectrometer (GC-MS) equipped with HP-88 capillary column following potassium hydroxide/methanol (KOH/MeOH) methylation. Based on optimization and appraisal of the characteristics of GC-MS, thirteen C18 trans fatty acid methyl ester (FAME) standards were separated and verified in 23 min, validation experiments were also conducted. The correlation coefficient was R2 ≥ 0.99 in the linear range of each FAME. At the low, medium and high fortification levels, recoveries fell within 90-119%. The relative standard deviations were below 9% for all 13 FAMEs. Low limits of detection (0.001-0.002 g/100 g) and quantification (0.002-0.007 g/100 g) were readily achieved. The content of C18 trans fatty acid isomers in pressed and solvent extracted oils were analyzed using this method.