E-Thesis 177 views 50 downloads
Ion structure determination using novel time-of-flight techniques and mass-analysed ion kinetic energy spectrometry. / Jonathan Paul Williams
Swansea University Author: Jonathan Paul Williams
-
PDF | E-Thesis
Download (4.53MB)
Abstract
Mass spectrometry is a powerful analytical technique that possesses the capability of molecular characterisation of complex mixtures. The technique has been the method afforded in this study for the characterisation of such mixtures of industrial relevance. The last decade has seen an important revi...
| Published: |
2000
|
|---|---|
| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | Ph.D |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa42653 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Abstract: |
Mass spectrometry is a powerful analytical technique that possesses the capability of molecular characterisation of complex mixtures. The technique has been the method afforded in this study for the characterisation of such mixtures of industrial relevance. The last decade has seen an important revival of one area in particular, time-of-flight mass spectrometry, which has had a significant impact on the field of mass spectrometry. This has been largely due to two recently developed ionisation methods, namely electrospray and matrix-assisted laser desorption ionisation. These ionisation methods have led to the development of novel time-of-flight mass spectrometer designs by commercial manufacture's, which take advantage of the theoretically unlimited mass range and the acquisition of a full mass spectrum every injection pulse of ions. Matrix-assisted laser desorption and electrospray ionisation have been interfaced to two novel time-of-flight mass analysers, the 'Autospec' oa- ToF, a hybrid sector orthogonal-acceleration time-of-flight instrument and the 'LCT', a liquid chromatograph time-of-flight instrument, manufactured by Micromass U.K., Ltd respectively. They have been successfully used to investigate and fully characterise complex systems of industrial significance. The 'Autospec' oa-ToF was used for high-energy collision induced dissociation experiments. The high sensitivity of the time-of-flight analyser was very powerful in the detection of product ions produced from various synthetic polymer precursor ions. The detailed structural information produced will be shown to fully characterise the polystyrene samples studied. An expanding area of mass spectrometry is electrospray ionisation used with orthogonal acceleration time-of-flight. The two methods when used in reflectron mode have significantly removed early limitations on resolution that time-of-flight mass analysers initially possessed. Sampling the electrosprayed ions orthogonally results in an increased duty cycle, which can be advantageous if fast chromatography is required. Evaluation of the LCT instrument, will be shown to provide mass resolution of the order of 5000 at full-width half maximum, mass accuracies of the order of 5ppm, full scan sensitivity equal to that of a quadrupole instrument in single ion monitoring mode and the detection of singly charged ions greater than m/z 10000. The research unit at Swansea University allowed the opportunity to investigate ion structural problems on an instrument built in house of BEE geometry. The energy released upon metastable fragmentation, leading to the formation of C3H3+ ions formed in some simple organic molecules yield peak shapes of a composite nature. The selection of ions from the translational energy-release distribution produced, have been investigated by consecutive reactions and will be shown to fully characterise isomeric ion structures. |
|---|---|
| Keywords: |
Analytical chemistry. |
| College: |
Faculty of Science and Engineering |