A new class of perfluorinated acid contaminants: Primary and secondary substituted perfluoroalkyl sulfonamides are acidic at environmentally and toxicologically relevant pH values
Bibliographic record
Abstract
The SPARC software program was validated for nitrogen-hydrogen acidity constant estimation of primary and secondary sulfonamides against a broad suite of substituted derivatives with experimental datasets in water and dimethylsulfoxide solvent systems and across a wide pK(a) range. Following validation, amidic proton pK(a) values were estimated for all C(1) through C(8) congeners of five major perfluoroalkyl sulfonamide classes: unsubstituted sulfonamides, N-methyl and N-ethyl sulfonamides, sulfonamidoethanols, and sulfonamidoacetates. Branching of the perfluoroalkyl chain is expected to have substantial impacts on amide moiety acidity in these contaminant groups, with intrahomologue variability of up to four pK(a) units and increasing pK(a) values with both increasing chain branching and greater proximity of the chain branching to the sulfonamide head group. Perfluoroalkyl chain length is not predicted to have a substantial influence on sulfonamide acidity. The predicted pK(a) values and variability are anticipated to have substantial impacts on the environmental partitioning and degradation of these compounds, as well as the modes and magnitudes of toxicological effects. Substantial pH dependent isomeric fractionation of perfluoroalkyl sulfonamides is expected both in situ and in vivo, necessitating the incorporation of amide group acidities in multimedia environmental models and pharmacokinetic studies.
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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 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".