| Abstract: | The development of tandem mass spectrometry (MS-MS) and its combination with gas chromatography (GC-MS-MS) has greatly enhanced our ability to analyze exceedingly complex mixtures from a wide variety of sources, including fossil fuels. This paper describes a comparison of the conventional electron impact (El) mass spectral fragmentation patterns, obtained in the MS-MS precursor – product mode, of three oleanane isomers and one ursene, all of which are used as indicators of higher plant input to the sedimentary environment Results show that El and collision-activated dissociation (CAD) spectra are most similar at collision energies between ?15 and ?20 eV.The presence of methyl substituents in these pentacyclic terpenes plays an important role in the process of ring fragmentation: the daughter spectra of the M – 15 fragments can be used to obtain structural information, such as the positions of the double bonds. |
