Designing working standards for stable H, C, and O isotope measurements in CO <sub>2</sub> and H <sub>2</sub> O
Bibliographic record
Abstract
RATIONALE: We address here the selection, preparation, calibration, storage, and use of carbonate and water working standards (WSs) for stable H, C, and O isotope measurements requiring the best possible precision and accuracy vs international reference materials (iRMs). This may be of interest for laboratories working intensively in the domains of the carbon and water cycles and of paleoclimate. METHODS: O values, respectively, are normally used. In both cases, a strict protocol must be followed to properly qualify the WS vs the current international isotopic scales, and much attention must be paid to calculating rigorous estimates of final uncertainties on these scales. RESULTS: Two specific protocols for the selection of carbonate and water WSs are detailed. Equations for a proper estimate of uncertainties are proposed. CONCLUSIONS: The selection of WSs involves a preselection of potentially suitable materials based on initial estimates of their mineralogical, chemical, and isotopic properties and long-term stability, based on literature or previous measurements. Their precise characterization vs international isotopic scales requires a thorough analytical work in a correct sequence. When properly carried out, the proposed protocols should permit WSs to be obtained, defined vs the VSMOW and VPDB scales, with uncertainties comparable with those achieved for the characterization of iRMs.
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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 | 0.032 | 0.032 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.004 | 0.003 |
| Science and technology studies | 0.002 | 0.004 |
| Scholarly communication | 0.003 | 0.003 |
| Open science | 0.003 | 0.004 |
| Research integrity | 0.004 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.005 |
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".