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Dissertation
Some quantitative aspects of the analysis of synthetic polymers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry
Doctor of Philosophy (Ph.D.), Drexel University
1998
DOI:
https://doi.org/10.17918/00000807
Abstract
Discrimination in the response of synthetic polymer samples in MALDI was investigated using two-component, low molecular weight polymer blends. A survey of several blends indicates that there are both mass and molecular weight distribution dependent parts of discrimination. The calculated blend component molecular weights and absolute and molar area responses reveal different aspects of discrimination and suggest some probable causes. A more detailed examination is made of a poly(ethylene glycol) blend system: PEG 1500/PEG 4600 using 2,5-dihydroxybenzoic acid (DHB) as matrix. A factorial experiment was performed about a center point of equal molar polymer amounts. PEG 1500 exhibited a linear increase in response with amount but the other factors tested affected the slope. PEG 1500 had no influence on the response of PEG 4600 and showed no interaction effects with the matrix amount or laser fluence. PEG 4600 exhibited saturation in its area response and had a strong inhibiting effect on the response of PEG 1500. It also influenced the effects of the matrix and laser fluence. The molar responses of the two blend components are unequal over much of the region of factor space investigated, but there is at least a limited region of minimal discrimination. The most important factor defining this region appears to be the high matrix level. Other experiments show that a nearly equal molar response can be maintained at even higher matrix levels, but that this is subject to the influence of the laser fluence level. The cation (sodium) level also affects the relative response and is another variable to consider in minimizing discrimination. The response saturation behavior of the two PEG components is consistent with an important, but probably not exclusive, influence of polymer aggregation on that effect and on the inhibiting effect of PEG 4600 on PEG 1500. The causes of response saturation and response inhibition are at least partially separable from the causes of unequal molar response. There are conditions under which the former affect the responses of both components in a proportional manner, while the latter must by definition affect the responses in a non-proportional manner.
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Details
- Title
- Some quantitative aspects of the analysis of synthetic polymers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry
- Creators
- Robert J. Goldschmidt
- Contributors
- Kevin Glenn Owens (Advisor)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xx, 264 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- College of Arts and Sciences; Chemistry; Drexel University
- Other Identifier
- 991014970213304721