Identification of 2‐hydroxy fatty acids in complex mixtures of fatty acid methyl esters by mass chromatography
Repetitive mass spectrometric scanning of gas‐liquid chromatographic effuents at short (6 to 15 s) intervals, with a digital computer for data acquisition, reduction and display, allows plots (mass chromatograms) to be made of the intensities of specific ion fragments. Plotting of m/e values characteristic for certain classes of compounds and/or individual components reveals the location of constituents in the gas chromatogram. This technique was applied to the identification of trimethylsilyl derivatives of unsubstituted and 2‐hydroxy fatty acid methyl esters in mixtures obtained from acid catalyzed methanolysis of cat brain galactocerebrosides. The plot of total ionization intensity vs scan number generated the gas‐liquid chromatogram. Mass chromatograms of m/e 73 and [M – 59]+ gave the locations in the gas‐liquid chromatogram of the hydroxy fatty acid derivatives, and mass chromatograms of m/e 74 and [M]+ located the unsubstituted fatty acid derivatives. Integrated ion intensities were used to determine the composition of the mixture of fatty acids. Copyright © 1974 John Wiley & Sons, Ltd.