Refine
Year of publication
- 2025 (1)
Document Type
- Doctoral Thesis (1)
Language
- German (1)
Has Fulltext
- yes (1)
Is part of the Bibliography
- no (1)
Keywords
- Kernresonanzspektroskopie (1)
- Mikroplastik (1)
- NMR (1)
The production and use of polymeric materials have been increasing continuously for
years. At the same time, the entry of microplastics (MP) – tiny particles resulting from the
wear and tear of these materials – into our environment is growing as well. By now,
awareness of MP has reached broad sections of the population and also research and
development on this field are similarly becoming increasingly important. However,
insufficient standardization and the lack of suitable analytical methods still make
recording and tracking of MP difficult, so that it remains largely unregulated. Mass-based
analytical methods are particularly advantageous for the establishment of legal
regulations. Apart from thermogravimetric methods, however, there are currently few
alternatives in this field. In this context, the use of nuclear magnetic resonance
spectroscopy (NMR), previously only qualitatively applied to MP, has now also been
examined for its quantitative benefits. This work deals with the current state of
quantitative NMR spectroscopy (qNMR) and tests possibilities for optimization and further
development for this purpose. Initially, the reduction of sample volumes and thus
minimized effort and measurement time of the method will be examined by combining
different polymer types into simultaneously measurable groups, as well as the suitability
of homopolymer calibrations for the detection of copolymers. Existing restrictions during
measurement will be adopted, and thus extractive procedures for sample preparation are
implemented. Finally, the influence of real environmental samples will be assessed, and
measures to reduce interfering factors will be taken in to account. As a result, the method
encompasses at least six polymer types, from PMMA, PS, BR, and PVC to PA and PET, as
well as separate approaches for polymers such as PAN and LDPE. A modular sample
preparation protocol, including extractive fractionation into measurement groups and a
chemical digestion method for matrix reduction, will be established and expanded to
include options for diffusion measurement and application to low-field instruments.
Practical application will be presented using real-world examples, such as freshwater
biofilms, as well as the use for quality control of certified reference materials.
Furthermore, initial insights into future development possibilities, like for the detection of
tire abrasion, will be provided.