A Gas Chromatography/Electron lonization-Mass Spectrometry-Selected Ion Monitoring Method for Determining the Fatty Acid Pattern in Food after Formation of Fatty Acid Methyl Esters

摘要

A method using gas chromatography/electron ionization-mass spectrometry(GC/EI-MS)in the selected ion monitoring(SIM)mode was developed for the analysis of fatty acids as methyl esters(FAMEs)in order to determine their percentage contribution to the fatty acid profile in food.In the GC/EI-MS-SIM mode,saturated fatty acids were determined with m/z87,monoenoic fatty acids were determined with m/z 74,and polyenoic fatty acids were determined via the sum of m/z 79 and m/z 81.The ratios of these fragment ions and the GC retention data provided additional information for tentative structural assignments.The 28 FAME standards tested provided similar results for the novel GC/EI-MS-SIM method and GC/EI-MS in the full scan mode,both of which were slightly worse than GC/flame ionization detection(FID).Analysis of sunflower oil,suet,and cod liver oil verified that both major and minor fatty acids(20-60% and down to 0.001 % contribution to the fatty acid pattern)were determined with sufficient quality that justifies application of the GC/EI-MS-SIM method for the analysis of food samples.Furthermore,the method was approx20-or approx10-fold more sensitive than GC/ EI-MS in the full scan mode or GC/FID,respectively.The method is suited for both quantitative purposes and fatty acid identification in samples where only low amounts of lipids are available.