GC/MS Quantitation of Diamondoid Compounds in Crude Oils and Petroleum Products
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Bibliographic record
Abstract
This study presents a quantitative gas chromotography/mass spectrometry (GC/MS) method for the analysis of adamantane, diamantane, and their alkylated homologues in 14 crude oils and 22 petroleum products including light and mid-range distillate fuels, residual fuels, and lubricating oils collected from various sources. The method detection limits for five target diamondoids were in the range of 0.06 to 0.14 μ g/g oil. The total concentration of adamantane and its 16 alkylated homologues commonly range from approximately 40 to 500 μ g/g in most crude oils and from 0.6 to 1,300 μ g/g in refined products, but reaching values of up to 2,000 μ g/g for the south Louisiana crude oil and the Jet A fuel. Diamantanes occur in all crude oils and lighter to middle distillates, and their total concentration was in a range of 5 to 200 μ g/g and with maximum values near 600 μ g/g in weathered diesel fuel, but they were not detected in very light distillates and most lubricating oils. Laboratory distillation of crude oils demonstrated that adamantane series were highly enriched in the diesel distillation range between 180 to 287°C, while diamantanes were largely found in the distillation fraction from 280 to 320°C. The concentrations of five groups of biomarker compounds in the saturated hydrocarbon fraction decrease in the order of sesquiterpanes > terpanes ≥ steranes > adamantanes > diamantanes for most crude oils, while their concentrations in various refined products differ widely. The absolute concentrations of diamondoid compounds and their molecular indices offer potential diagnostic means for oil source identification and oil correlation, particularly for lighter refined products such as jet and diesel fuels in which the high molecular weight biomarkers have been removed during the refining processes.
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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 | 0.000 | 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) | 0.000 | 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 it