pH-Dependent Molecular Behaviors of a New Potential Color Additive: 4{[6-(1-carboxyethyl)-2-hydroxy -1-naphthyl]diazenyl}-3,5- dinitro Benzoic Acid
Bibliographic record
Abstract
Phenyl azo hydroxynaphthalene (PAHNP) is the pharmacophore in certain color additives (e.g. sunset yellow, FD & C yellow No. 6) approved for use in human foods, drugs and cosmetics. The azo compound, 4{[6-(1-carboxyethyl)-2-hydroxy -1-naphthyl] diazenyl}-3,5-dinitrobenzoic acid (AZ-03) is a new, non-genotoxic, PAHNP analog, in a mono-azo chemical library. Process understanding of pH dependent behaviors of the highly functionalized molecule, is a critical aid to its identification. Absorption spectra of a fixed concentration of AZ-03 [3.30 x 10-5 M] in buffer solutions of varied pH were recorded. Spectra overlay suggested isosbestic point exists around 520 nm. Absorbance measurements of solutions (1.10 x 10-5 M) of pH 7, 10 and 11 were taken at 522, 524, 526 and 528 nm. Relative contribuiton of variables to overall variance was; wavelength (7%, p = 0.16), pH of media (57%, p < 0.0001), interaction between pH and wavelength (7%, p = 0.46, 2-way ANOVA, Bonferroni test). The probability that signal difference across pH was due to chance was 4 times greater at 522 nm (p=0.29) relative to 524 nm (p=0.08, 1-way ANOVA). The orange, unionized specie and violet, ionized specie both exhibited intense absorption, with molar absorptivities of 14,600 (490 nm) and 12,800 (550 nm) [L mol-1 cm-1 ] respectively. AZ-03 was degraded by pseudo first-order kinetics in alkaline medium by specific-base catalysis. It was shown with some statistical rigor that the dye exhibits isosbestic point at 522 nm . Base-catalyzed degradation gave a non-linear and diagnostic rate-pH profile. These findings could aid precise authentication of this potential color additive, and thus facilitate further understanding and studies of its solution chemistry.
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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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".