Ammonia and Amines: Phase Partitioning, Oxidation Chemistry in Aqueous Phase and Atmospheric Measurement in Urban Canada
Bibliographic record
Abstract
Alkyl amines are recognized for their important roles in the atmosphere, influencing particle formation, aerosol composition, and human health impacts despite their low ambient abundance. To advance understanding of their atmospheric fate, this thesis brings together three projects focused on the oxidation kinetics, thermodynamic behaviour, and analytical detection of reduced nitrogen species. In the first project, laboratory measurements of the aqueous-phase oxidation kinetics of dimethylamine (DMA), diethylamine (DEA), and ammonia with hydroxyl radicals (OH) were conducted using relative rate methods. Rate constants for both protonated and neutral forms were determined, enabling estimation of their atmospheric lifetimes in aerosols and cloud droplets. Preliminary experiments showed that oxidation of larger amines under acidic conditions produces smaller amines and ammonia, suggesting previously unrecognized secondary formation pathways different from gas phase oxidation. The second project examined the seasonal and temporal variation of particulate DMA and DEA in urban Toronto over a 1.5-year observation period, assessing their mass loadings as a function of particle size. They were found predominantly in particles with diameters less than 1.8 µm, but the molar ratios of amines to ammonium were between 10⁻¹–10⁻⁴, with the highest ratios occurring for the smallest particles. Predictions of gas–particle partitioning using the Extended Aerosol Inorganics Model (E-AIM) showed good agreement with field observations, highlighting the value of thermodynamic modelling for interpreting phase behaviour. The third project developed and optimized a precolumn derivatization HPLC-MS method for improved detection of a broader range of reduced nitrogen compounds. Applying this method to PM₂.₅ samples from a poultry research facility demonstrated its effectiveness for identifying and quantifying diverse reduced nitrogen species in complex environmental matrices. Together, this work investigated key aspects in the atmospheric chemistry of alkyl amines, providing new insight into their transformation, partitioning, and detection in both laboratory and real-world environments.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.003 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".