<sup>31</sup> P NMR and ESI-MS studies of metal ion-phosphorus pesticide residue complexes
Bibliographic record
Abstract
31 P NMR and ESI-MS structural studies have been carried out for O,O-dimethylphosphorothioate anion (PA – ) interacting with Ag + , Hg 2+ , and Na + cations. Evidence is presented for the formation of PA – ···Ag + and PA – ···Hg 2+ metal complexes and for ionic PA – Na + , with 31 P chemical shift values of 43, 40, and 65 ppm, respectively. The 31 P chemical shifts for PA – ···Ag + and PA – ···Hg 2+ complexes exhibit an initial sharp rise as the [Ag + ]/[PA] and [Hg 2+ ]/[PA] ratio increases from 0 to 1.0 and 0 to 0.5, respectively, and remain almost constant beyond these ratios. These results indicate the formation of 1:1 PA – ···Ag + and 2:1 (PA – ) 2 ···Hg 2+ complexes. Electrospray ionization mass spectroscopy (ESI-MS) revealed peaks corresponding to [O-P(=S)(OCH 3 ) 2 + Ag + H] + and {2[O-P(=S)(OCH 3 ) 2 ] + Hg + H} + for PAH interacting with Ag + and Hg 2+ , supporting the 1:1 PA – ···Ag + and 2:1 (PA – ) 2 ···Hg 2+ stoichiometry. The experimental results support the predominance of species with greater P=O double bond and P–S single bond character, relative to P-O/P=S. Our results on 31 P NMR chemical shifts have a bearing on the use of 31 P chemical shifts as a tool for organophosphorus pesticide identification.
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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 | 0.000 | 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) | 0.007 | 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".