Wright, Andrew David (1989) Chemical ionization and collision induced dissociation mass spectrometry. PhD thesis, University of Warwick.

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Abstract

The work contained in this thesis covers two aspects of mass spectrometry, namely chemical
ionization (CI) and collision induced dissociation (CIO). Chapter 2 deals with an
investigation into the CI mass spectra of tetraisopropyl methylenebisphosphonate recorded
using mixtures of argon and dimethylamine as the reagent gas. Comparison of the mixed gas
spectra with those obtained using the individual gases revealed additional fragmentation in
the case of the mixed gases. The conclusion drawn from the study is that the dilution of
dimethylarnine with argon causes the formation of additional protonating species of lower
proton affinity than dimethylamine which can undergo more exothermic proton transfer
reactions with the sample. Chapter 3 reports a comprehensive study of the chemical
ionization mass spectra of urethanes. Four main classes of fragment ions are found in the
spectra and the mechanisms for their formation are postulated. Evidence for these
mechanisms is obtained from parallel studies of methyl carbamates and from a CIO study. A
study of the effects of the collision gas on the CIO mass spectra of leucine-enkephalin is
presented in chapter 4. The collision gases used were helium, argon, krypton and carbon
tetrafluoride The monatomic gases used cause more fragmentation of the peptide ion as the
mass of the collision gas is increased. Conversely, when a poly atomic species is used, the
CIO spectra resemble those acquired using a much less heavy target gas. Two possible
explanations are proposed. Either the additional internal energy which would be expected to
be transferred to the incident ion is absorbed by vibrational modes of the target molecule, or
that the amount of energy transferred during the collision is dependent on the particular atoms
of the colliding species rather than their overall masses. The final chapter of this thesis is a
report of the development of new linked-scan equations for the detection of fragment ions
resulting from CID in the first field-free region of a forward geometry mass spectrometer.
These scan laws and terms relating to the size of the translational energy losses are
incorporated into the calibration software for use with a commercial mass spectrometer.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Mass spectrometry, Chemical ionization mass spectrometry
Official Date:	October 1989
Dates:	Date Event October 1989 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Jennings, Keith R.
Sponsors:	Science and Engineering Research Council (Great Britain) (SERC) ; Kratos Analytical (Firm) ; British Mass Spectrometry Society
Extent:	xvii, 105 leaves
Language:	eng

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