Thesis-2008-Dolci.pdf (17.78 MB)
Liquid Chromatography–Mass Spectrometry analysis of oligolactic acids
thesis
posted on 2018-10-29, 12:54 authored by Monica DolciThe project has demonstrated the application of liquid chromatography coupled to
mass spectrometry (LC–MS) for the characterisation of oligolactic acids (OLAs),
employed as pharmaceutical excipients in metered dose inhalers.
OLAs proved to be difficult to characterise because of their complexity, which was
ascribed. to the presence of repeated structural monomeric units and a nonrepeating
moiety (the head group). Furthermore, during the course of method
development the potential presence of degradation products and impurities had to
be considered for quality control purposes.
Various LC–MS methods were developed to target both oligomeric distribution and
head group functionalities of OLAs.
Liquid chromatography at critical conditions (LCCC), aimed at addressing the
head group distribution of OLAs, led to the separation of the cyclic impurities from
the parent linear molecules. However, to successfully achieve a complete
characterisation of OLAs, a second separation targeting the oligomeric distribution
was investigated.
Hydrophobic and polar interactions and possible solvation effects, which regulate
RP–HPLC separation mechanisms, proved to be able to offer the selectivity
necessary to resolve OLAs in terms of their size and their head groups, leading to
the simultaneous separation between the linear molecules and their cyclic
impurities and the determination of oligomeric distribution.
Funding
3M Health Care Ltd.
History
School
- Science
Department
- Chemistry
Publisher
© Monica DolciPublisher statement
This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/Publication date
2008Notes
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy at Loughborough University.Language
- en