Chemical Composition of Athabasca Bitumen: The Distillable Aromatic Fraction
Bibliographic record
Abstract
The volatile aromatic fraction (240 °C and 10 –3 Torr pressure) of Athabasca bitumen was separated via thin-layer chromatography (TLC) (Ag + /SiO 2 ), followed by alumina column chromatography, into 13 mono-, di-, and triaromatic subfractions, each of which was subjected to field ionization mass spectrometry (FIMS) analyses. Altogether, close to 6000 constituent molecules, ranging in molecular weight from 200 to ∼800 Da, have been observed, including the partially and fully aromatized, ring-opened, and truncated derivatives of essentially all of the saturated biomarkers detected here or earlier in the saturated fraction of this bitumen. All molecules detected were of aromatic character, with the exception of a complex suite of cyclic terpenoid (and steroid) sulfides, having adsorptive properties similar to those of the triaromatic hydrocarbons. In several cases, the FIMS analyses were supplemented by conventional biomarker analyses and a novel biomarker analysis, employing basic aqueous extraction of the whole oil sands. The high-molecular-weight portion (MW > 482 Da) of each subfraction isolated (which usually does not show up in conventional biomarker analyses) varies in concentration from a few to about 10 wt %. This fraction may arise from processes analogous to the combination reactions occurring in the addition of biomarker molecules to asphaltene by C–C, C–S–C, and C–O–C covalent bond formation. In the present system (with the exception of the cyclic sulfides), only C–C bond additions can be operative.
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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 | 0.000 | 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".