Towards Multiplexed Nuclear Magnetic Resonance for Environmental Analysis

Nuclear Magnetic Resonance (NMR) is one of the most powerful analytical tools in modern research. Within the scope of environmental analysis, NMR can identify unknown pollutants, examine non-covalent binding in soils and, uniquely, study biochemical changes in living organisms. Here, novel approaches are explored to address current challenges and further improve the utility of environmental NMR. The ability to study organisms in vivo (meaning while they are alive) was applied to track metabolic changes in the critical species Daphnia magna. Specifically, a novel pulse sequence that allows the selection of chosen compounds out of a complex mixture was employed, addressing the key challenge of spectral overlap. This powerful technique was used to follow the biochemical impacts of external stressors by tracking changes in key metabolites (e.g., glucose). Another novel “slice-selective” pulse sequence was developed and used to non-destructively examine specific parts of a larger sample. The uptake of 13C enriched food in an earthworm (Eisenia fetida) was studied, and there were considerable biochemical differences in uptake across different body parts, which would have been missed with standard approaches. Following this, the focus shifted to specialized NMR hardware called microcoils. These devices greatly improve sensitivity for very small samples such as D. magna eggs (<400 μm in diameter) which are critical to aquatic ecosystem health. Cutting-edge complementary metal-oxide-semiconductor (CMOS) technology was used to create microcoils tailored to studying these eggs. The CMOS microcoils showed considerable potential including excellent sensitivity, the ability to analyze many different nuclei, and facile expansion to multiple coil arrays. The latter refers to multiple coils for the study of multiple samples at the same time, which addresses the low throughput of single microcoil approaches. A three coil CMOS array was used to study three D. magna eggs simultaneously for the first time, laying the groundwork for improved throughput and allowing concurrent analysis of control and exposed organisms, reducing variability in toxicological studies. In combination, the approaches detailed here improve the applicability of NMR to environmental research, paving the way for future efficient study of microscopic samples, whether they be aquatic eggs, cells, or even air particles.

Department dc:contributor.department

Chemistry

Year dc:date.issued

2025

Author dc:creator

• Lysak, Daniel Henryk

Advisor dc:contributor.advisor

• Simpson, Andre J

• CMOS
• in vivo
• microcoil
• Nuclear Magnetic Resonance
• singlet
• slice selection

Statement dc:rights

• Attribution-NonCommercial-ShareAlike 4.0 International

Licence dc:rights.uri

• http://creativecommons.org/licenses/by-nc-sa/4.0/

Handle dc:identifier.uri

https://hdl.handle.net/1807/149936

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/149936