Isotopic Fractionation of Sn during Methylation and Demethylation Reactions in Aqueous Solution
Bibliographic record
Abstract
Laboratory experiments, modeling the methylation of inorganic Sn(II) by methylcobalamin and the decomposition of methyltin under irradiation with UV light in aqueous solution, have been performed. Methyltin has been separated from inorganic Sn using anion-exchange chromatography and subjected to Sn isotope ratio measurements via solution nebulization multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The methylation of Sn(II) in the dark was accompanied by mass-dependent Sn isotopic fractionation, which resulted in preferential partitioning of the lighter Sn isotopes into the organic phase, with a shift of approximately 0.57 +/- 0.12 per thousand in terms of delta124/ 116Sn between methylated and inorganic Sn. The methylation of Sn(II) by methylcobalamin under UV irradiation resulted in the accelerated formation of methyltin in the beginning of the process, but was followed by the photolytic degradation of methyltin until its complete mineralization. The photolytic degradation of methyltin in the presence of methylcobalamin and inorganic Sn(II) was slower than that of pure solutions of commercially obtained monomethyltin. This is attributed to the methylating action of methyl radicals produced from photolytically decomposing methylcobalamin. Both synthesis and decomposition of methyltin under UV irradiation were accompanied by both mass-dependent and mass-independent Sn isotopic fractionation, with the latter due to the magnetic isotope effect. As a result of this, the lighter Sn isotopes preferentially partition into reaction products, while the odd isotopes, 117Sn and 119Sn, are selectively enriched relative to the other isotopes in the starting molecules. The extent of the observed variations in the isotopic composition of Sn is larger than that documented previouslyfor geological and archeological samples. These results indicate that Sn isotopic fractionation between various chemical forms of Sn in the natural aquatic systems may be significant and can provide new insights into the biogeochemical cycling of the element.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.000 | 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) | 0.001 | 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".