UV Photolytic Mechanism of <i>N</i>-Nitrosodimethylamine in Water: Dual Pathways to Methylamine versus Dimethylamine
Bibliographic record
Abstract
The direct ultraviolet (UV) photolysis of N-nitrosodimethyl-amine (NDMA), a well-known potential carcinogen, was investigated in aqueous solution with its degradation products analyzed quantitatively. NDMA is known to be photolyzed either to dimethylamine (DMA) or to methylamine (MA) by two distinct pathways. However, the mechanism through which NDMA is photolyzed to DMA is still not clearly understood. This study reveals a new mechanistic pathway of NDMA photolysis to DMA by identifying the factors influencing the photolysis pathway. The two pathways of NDMA photolysis were found to be strongly dependent on the initial NDMA concentration and solution pH. Increasing the initial NDMA concentration clearly favored the DMA formation path. DMA production was optimized in the region of pH 4-5. The nitrite ion (NO2-) produced from the NDMA photolysis was identified as a key reagent in directing the NDMA photolysis toward DMA production. The observed photolytic behaviors of NDMA photolysis could be successfully explained in terms of the new mechanism involving the role of NO2-.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 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 | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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; both teacher heads agree on what is shown here.
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".