Investigation of Aqueous-Phase Photooxidation of Glyoxal and Methylglyoxal by Aerosol Chemical Ionization Mass Spectrometry: Observation of Hydroxyhydroperoxide Formation
Bibliographic record
Abstract
Aqueous-phase processing of glyoxal (GLY) and methylglyoxal (MG) produces highly oxygenated, less volatile organic acids that can contribute to SOA formation and aging. In this study, aerosol chemical ionization mass spectrometry (aerosol CIMS) is employed to monitor aqueous-phase photooxidation of GLY and MG. Using iodide (I(-)) as the reagent ion, aerosol CIMS can simultaneously detect important species involved in the reactions: organic acids, peroxides, and aldehydes, so that the reconstructed total organic carbon (TOC) concentrations from aerosol CIMS data agree well with offline TOC analysis. This study also reports the first direct detection of hydroxyhydroperoxide (HHP) formation from the reaction of H(2)O(2) with GLY or MG. The formation of HHPs is observed to be reversible and an estimate of their equilibrium constants is made to be between 40 and 200 M(-1). Results of this study suggest that HHPs can form additional formic acid and acetic acid via photooxidation and regenerate GLY or MG during photooxidation, compensating their loss. HHP formation needs to be further studied for inclusion in aqueous-phase chemical models given that it may affect the aqueous partitioning of carbonyls in the atmosphere.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 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".