CHARACTERIZATION OF ORGANIC CONSTITUENTS OF ENVIRONMENTAL FILMS BY GC/MS
Bibliographic record
Abstract
The work of this thesis focuses on the further characterization of organic films that develop on the exterior and interior surfaces of windows in urban and rural areas. Previous work by our group has shown that these organic films contain organic contaminants (PAH, PCBs, OC pesticides, etc.), and air particulate material. Simulated precipitation experiments have shown that the organic film is easily washed off and that these contaminants enter surface waters, ultimately finding their way into sediments in rivers, lakes and oceans. Samples of organic films on windows were collected at numerous sites in the Toronto area between July 2000 and July 2001. Previous work led to the quantification of over 85 target analytes within these film samples including, n-alkanes, n-alkanoic acids, n-alkanoic diacids, unsaturated alkanoic acids, aromatic carboxylic acids and resin acids. Crude methanol extracts of these film samples were derivatized (MeONH2*HCl in pyridine, 37°C, 90 min. followed by N-trimethylsilyl-N-methyltrifluoroacetamide (MSTFA), 37°C, 30 min.) and analyzed by GC/MS in full scan EI+ mode. Twenty seven compounds were positively identified with authentic standards, showing excellent matches to mass spectra and retention index values. These compounds included sugars (arabinose, glucose, fructose, sucrose, trehalose), sugar alcohols (xylitol, pinitol, quebrachitol, inositols), acids (glyceric, benzoic, fumaric, succinic, malic, adipic, azelaic) and a number of other unidentified derivatives. A total of 103 unique peaks were observed in 12 window film samples. It appears that these compounds are of plant origin owing to the identification of plant sterols, β-sitosterol and stigmastanol. In addition, the wood combustion marker, levoglucosan, was identified in all but one film sample. The patterns of polar compounds identified in these films are similar to recent findings of these substances in air particulate. The profiles of these polar compounds in three Hamilton PM10 samples were similar to literature reports. The contribution of these newly identified compounds to the film exceeds or greatly exceeds the contribution of all previously identified chemical substances. There remains a significant amount of unidentified material in these films. The importance of these films lies in their pivotal role in the sequestering, transport and fate of organic contaminants in urban 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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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; 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".