Measurement of Low Air−Water Partition Coefficients of Organic Acids by Evaporation from a Water Surface
Bibliographic record
Abstract
A novel system is described for the determination of the air−water partition coefficient ( K AW ) for substances that have low air−water partition coefficients, i.e., K AW < 10 -3, and may aggregate in solution, ionize, and display surface activity. The compound is evaporated isothermally from solution through an undisturbed air−water interface at a known gas flow rate, and its concentrations in the water and gas phases are measured. Although equilibrium is not achieved, the extent of departure from equilibrium can be determined using estimated mass transfer coefficients. K AW was determined for formic, acetic, benzoic, and perfluorooctanoic acids (PFOA), and assuming an approximately 50 % approach to equilibrium, which is in accord with theoretical prediction. Agreement with available literature data was satisfactory. The experimentally determined K AW of PFOA was 1.02·10 -3 with a standard deviation of 9.1 % ( n = 9). The method is suitable for fluorinated surfactants, aggregating and ionizing substances for which K AW may not be readily measured with existing techniques.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".