Method Development and application of total oxidizable precursor(TOP) assay for assessment of PFAS on paper and board food packaging
Bibliographic record
Abstract
Per and poly-fluoroalkyl substances (PFAS) have been detected in paper and board food packaging in Europe, the United States, Canada, and many other countries in Asia (Sapozhnikova et al., 2023). However, the screening of overall PFAS in consumer products is difficult because thousands of PFAS including unknown precursors are being used in various consumer products including paper and board food packaging, and the large proportion of unknown precursor compounds is overlooked by conventional target analysis methods. Total oxidizable precursor (TOP) assay is an efficient technique to determine the levels of unknown precursors by comparing the levels of perfluoroalkyl acid (PFAAs) before and after oxidation. In the current study, TOP assay has been applied to known food packaging-related precursors including 6:2 FTSA, 8:2 DiPAP, and NEtFOSAA. The effect of oxidation time on oxidation efficiency was observed at different time points 6 h, 18 h, and 24 h. At 18h and 24 maximum oxidation efficiency was seen. At increased amounts and concentrations of oxidation solution, 99.5% ± 0.03 of oxidation efficiency and 89%, 104%, and 110% of the molar yield of PFCA were observed for 6:2 FTSA, 8:2 DiPAP, and NEtFOSAA respectively. TOPA was applied on paper and board food packaging samples from Swedish supermarkets, the increased concentration of ƩPFAS was seen after TOP assay from the range of 0.15 ng/cm2 to 38.2 ng/cm2 which before TOPA was 0.00036 ng/cm2 to 1.38 ng/cm2 and also contributed in the identification of ƩPFAS in extractable organic fluorine (EOF) content after TOP assay. Direct total oxidizable precursor assay (dTOPA) was also applied on the food packaging to avoid potential losses during extraction, it resulted in a significant increase in ƩPFAS which indicated there might be side chain polymers that were not extractable with the primary method used for the extraction in the current study and after dTOPA those side chain polymers might have degraded into quantifiable ƩPFCA
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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 | 0.003 | 0.003 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 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".