A Passive Air Sampling Technique For Ultra-Trace Quantitation Of Gas-Phase Perfluoroalkyl Carboxylic Acids
Bibliographic record
Abstract
Perfluoroalkyl carboxylic acids (PFCAs) are persistent chemicals distributed ubiquitously in the environmental despite their anthropogenic origin. Recent studies have shown that atmospheric transport is an important transport mechanism for PFCAs. Despite this, measuring mixing ratios of gaseous PFCAs in the atmosphere has been an analytical challenge, limiting the availability of atmospheric measurements. A new nylon-based passive air sampling (PAS) technique addresses many of these challenges by offering a cost effective, low-labour solution. These samplers were calibrated for trifluoroacetic acid (TFA) in an atmospheric chamber and field measurements were compared to measurements from an ambient ion monitoring ion chromatography mass spectrometer, where good agreement was found. They were also deployed in various locations in Canada for gas-phase PFCA measurements which revealed many different trends, including the wastewater treatment plant as a point source of gas-phase TFA. These measurements have enhanced our understanding of PFCAs with calibrated, cost-effective samplers capable of ultra-trace measurements.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 0.002 |
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".