Determining the maximum environmental release limit of the toxic dye, CHPD
Bibliographic record
Abstract
The Canadian Environmental Protection Act, 1999 (CEPA, 1999) requires the Canadian government to categorize all substances on the Domestic Substances List (DSL). Under the Chemicals Management Plan, the Government of Canada addresses chemicals that had not previously undergone rigorous scientific assessment. One such compound, [[4-[[2-(4-cyclohexylphenoxy)ethyl]ethylamino]-2-methylphenyl]methylene]-, propanedinitrile, commonly known as CHPD (cyclohexylphenoxydinitrile), recently underwent a screening assessment and was declared to be “toxic” to the environment. As a result, the Government of Canada ordered the “virtual elimination” of CHPD from the environment. Thus, CHPD may not be present above the lowest concentration that can be accurately measured using sensitive, but routine, analytical methods. We present a solid-phase extraction (SPE) method to determine CHPD in water and wastewater effluent to establish the maximum environmental release limit for this toxic compound. Optimal extraction was attained using an ENVI-18 cartridge. Extracts were analyzed by HPLC–PDA and HPLC–MS/MS techniques; in both matrices, the PDA method had greater sensitivity, less susceptibility to matrix effects, lower limit of quantitation (LOQ) values, and could be successfully validated at multiple spike levels. The lowest concentration of CHPD that could accurately be measured was found to be 108 ng/L in extracts of pure water, using the HPLC–PDA system. Therefore, this value (108 ng/L) will inform regulations on the maximum environmental release limit for CHPD.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 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".