δ(<sup>18</sup>O/<sup>16</sup>O) Determinations in Water Using Inductively Coupled Plasma–Tandem Mass Spectrometry
Bibliographic record
Abstract
High Resolution Image Download MS PowerPoint Slide A fully validated measurement approach for the determination of oxygen isotope ratios in water using inductively coupled plasma–tandem mass spectrometry (ICP-MS/MS) is described for the first time. Deuterium was used as a reaction gas to mass-shift the oxygen isotopes to the OD 3 + product ion, allowing for the removal of polyatomic ions ( 16 O 1 H + and 16 O 1 H 2 + ) generated in the plasma that interfere on the less abundant oxygen stable isotopes ( 17 O and 18 O). The developed methodology was validated for δ VSMOW-SLAP ( 18 O/ 16 O) determinations using four internationally recognized IAEA reference materials, as well as 11 in-house laboratory isotope reference materials that were characterized by isotope ratio mass spectrometry and cavity ring-down spectroscopy. δ VSMOW-SLAP ( 18 O/ 16 O) values determined by ICP-MS/MS and the reference methods overlapped within the uncertainties and showed no significant difference for water materials with a low matrix load. Elevated levels of sodium, chloride, and silicon in the matrix lead to isotope ratio shifts of up to 12‰ in both the positive and negative directions. Additionally, comparisons with indicative values from the reference materials demonstrated that δ VSMOW-SLAP ( 17 O/ 16 O) determinations are also possible using the ICP-MS/MS approach. While the uncertainty of the developed approach (median uncertainty u c (δ VSMOW-SLAP ( 18 O/ 16 O)) = 0.70‰) is not currently able to match that of existing methodologies, it is envisioned that oxygen isotope ratio determinations can be performed alongside multielemental analysis by a wider community for applications where lower uncertainties are not required.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".