LIDI 2 – New Evaluation Strategy for Accurate and Precise Clumped Isotope CO2 Analysis on Carbonate Samples
Bibliographic record
Abstract
Long Integration Dual Inlet (LIDI) is an established technology which enabled improved accuracy and precision of Δ47 analysis from carbonate samples by utilizing sequential measurement of the full sample and reference, rather than alternating between sample and reference on shorter time periods, as it is done in the classical Dual Inlet method. As of today, there are two key challenges that were limiting further improvements to Δ47 determination: the IRMS must be in a stable temperature environment during long measurement of sample and reference gas, and the crimping of the sample and reference capillaries must be precisely matched, otherwise the produced data will be inaccurate and have reduced precision. Here we present the improvements made on the sample gas measurement and data evaluation, which we define as LIDI 2. By applying the LIDI 2 method, sample bracketing is possible following a four-step approach, resulting in fully corrected temperature drift (i.e. eliminated from the data), decreasing the standard deviation by factor of 2. This is a substantial improvement for acquiring clumped isotope data as reaching a very stable temperature of ±0.1°C/h is a challenge for most laboratories. Alongside eliminating variation in the Δ47 data caused by unstable laboratory air temperature, LIDI 2 also improves the overlap of sample and reference gas signals due to non-perfect crimping of the capillaries. The crimping procedure is laborious and rarely delivers perfect results. Additionally, the pressure adjustment before reference measurement must ensure there is no significant offset between sample and reference intensities. LIDI 2 delivers perfect sample versus reference intensity matching, which results in significantly higher precision on each sample gas analyzed. Standard error of a single sample measurement is improved by up to factor of 2. The LIDI 2 method delivers improved accuracy and precision on Δ47 measurement from small Carbonate samples, which in combination with the latest advancements in inert capillaries coating and automated contaminant trapping contributes to enhanced clumped isotopes data quality.
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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 | 0.004 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 0.003 |
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".