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Structural and analytical studies by tandem mass spectrometry

Madden, Tracey; (1991) Structural and analytical studies by tandem mass spectrometry. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

This thesis describes the use of several such tandem mass spectrometrical techniques, the majority including controlled collisions with a target gas to effect dissociation or charge exchange. A range of MS/MS techniques was utilized in the study of the fragmentation of [M-CO]+. ions from various positional isomers of the hydroxyquinoline molecular ion, and [M-CS] +. ions from various positional isomers of the mercaptoquinoline molecular ion. CID/MIKES spectra give evidence in favour of the [M-CO] +. and [M-CS] +. ions from the 2-, 3- and 4-isomers adopting an indole-like structure. Deuterium labelling experiments with the [M- CO] +. and [M-CS] +. ions showed the uniqueness of the two 2-isomers, which unlike the other positional isomers, gave no evidence of hydrogen scrambling. It has already been shown through the study of the metastable peak corresponding to the loss of CO from the molecular ion that 2-hydroxyquinioline is tautomeric with quinolin- (1H)-one. This type of study was extended to structurally related ions that also lost CO, revealing other instances of tautomerism and competitive routes for loss of CO from a single ion. A comparative study using various MS/MS techniques was carried out on the acetamide ion, comparing its structure with C2H5NO+. ions formed from N-ethylacetamide and n-butyramide by a McLafferty rearrangement. A similar study was made of t-butylbenzene, various techniques being used to investigate its fragmentation pattern and the structure of the ions formed. It has been reported that the analysis of mass spectral data from peptides is greatly aided by close examination of low mass peaks, particularly those due to immonium ions and other closely associated ions. Tandem mass spectrometry was used to study the effects of small changes in the peptide sequence on the relative abundances of these low mass ions.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Structural and analytical studies by tandem mass spectrometry
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
URI: https://discovery.ucl.ac.uk/id/eprint/10122663
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