Structural elucidation of complex organic compounds by the study of unimolecular and collision induced ion reactions in the gas phase

• Main Author: Bozorgzadeh, M. H.
• Published: Swansea University 1979
• Subjects: 543
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636139

The technique of mass-analyzed ion kinetic energy spectrometry (MIKES), in which ions are selected according to their mass-to-charge ratio before entering the electric sector of a mass spectrometer, has been used for structural studies on complex organic and biochemical compounds. This thesis contains three parts: (a) the application of MIKES to the structural elucidation of five unknown organic compounds; (b) an investigation to extend the MIKES technique to the structural analysis of specific portions of a molecule. Five steroids of known structure with similar ring skeletons and different side chains were studied. In each case, the ion products of the mass of the specific side chain was isolated by the MIKES technique followed by structural interpretation using the unique set of daughter ions in the MIKE spectrum. The ring skeletons were studied in the same way. The results demonstrated that unique parts of molecules can be isolated and their structures determined; and (c) the development of a new method, combining electron-impact pyrolysis mass spectrometry with the MIKES technique, for the structural elucidation of a complex biomacromolecule, deoxyribonucleic acid (DNA). This method (Py-EI-MIKES)' was used to study the structure of a modified nucleoside of unknown origin which is present in viral DNAs. Ion species from bacteriophage 0-174 DNA and lambda DNA were examined by Py-EI-MIKES. The MIKE spectra yielded evidence that a highly-modified nucleoside is present in both of these DNAs. The structure that the spectral data support is that of deoxy-Q*-nucleoside. Additional secondary projects resulted in: (a) a method for recognizing and eliminating extraneous peaks in MIKE spectra, and (b) a fast-scanning method for recording MIKE spectra under computer control for situations when the amount of sample and the time permitted for analysis are limited. This thesis contains four independent chapters and six publications.