Registration Dossier
Registration Dossier
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EC number: 607-520-2 | CAS number: 250640-08-5
Additional information on environmental fate and behaviour
Administrative data
- Endpoint:
- additional information on environmental fate and behaviour
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 2021
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
Data source
Reference
- Reference Type:
- study report
- Title:
- Unnamed
- Year:
- 2 021
- Report date:
- 2021
Materials and methods
Test guideline
- Qualifier:
- according to guideline
- Guideline:
- other: OECD 318
- GLP compliance:
- no
Test material
- Test material form:
- solid: nanoform, no surface treatment
- Details on test material:
- - Batch: PG10631
- Appearance: solid orange
- Shape of particles: see boundary composition
- Surface area of particles: BET 20.3 m2/g
- Crystal structure: crystalline
- Coating: none
- Expiry date: 2022
Constituent 1
Results and discussion
Any other information on results incl. tables
After 6h, the samples showed high dispersion stability in 0 mM Ca and at any Ca concentration at pH 9. For the samples at all other conditions the stability was intermediate
After 24 hours the stability at pH 9 regardless the Ca concentration remained high. The stability at pH 4 in 1 and 10 mM Ca became low. The stability at all other conditions was intermediate.
| Full results of the dispersion stability in the presence of NOM | |||||||
| Ca(NO3)2 | Stability after 6h | Standard deviation | Stability after 15h | Standard deviation | Stability after 24h | Standard deviation | |
| [mM] | [%] | [%] | [%] | [%] | [%] | [%] | |
| pH 4 | 0 | 99.2 | 0.3 | 93.1 | 0.9 | 73.0 | 5.7 |
| pH 4 | 1 | 21.3 | 2.0 | 9.7 | 1.2 | 7.9 | 0.9 |
| pH 4 | 10 | 19.1 | 1.0 | 9.3 | 0.7 | 7.6 | 0.8 |
| . | |||||||
| pH 7 | 0 | 101.5 | 0.9 | 98.9 | 1.3 | 88.2 | 1.8 |
| pH 7 | 1 | 89.1 | 3.0 | 83.0 | 2.1 | 82.9 | 3.0 |
| pH 7 | 10 | 73.3 | 0.7 | 70.9 | 0.6 | 71.8 | 0.3 |
| . | |||||||
| pH 9 | 0 | 104.1 | 3.7 | 103.8 | 3.5 | 106.4 | 3.2 |
| pH 9 | 1 | 100.7 | 0.2 | 100.1 | 0.0 | 102.5 | 0.7 |
| pH 9 | 10 | 100.9 | 2.4 | 101.0 | 2.4 | 101.3 | 2.4 |
To rationalize the observed dispersion stability, we finally checked the particle size distribution directly in the environmental medium. We applied the NanoDefine method of Analytical Ultracentrifugation (SOP AUC-RI). The centrifugation parameters are given in the methods section.
As required by TG318, paragraph 31, the tested nanomaterial was pre-wetted in ultrapure water and left in the form of wet-paste for 24 h. The TG318 requires this step “to insure the proper interaction of nanomaterial surface with ultrapure water.” We visually observed incomplete wetting, and so any ensuing measurement would have been incorrect. In accord with the NanoGenoTox dispersion protocol, a drop of ethanol was added, successfully transferred the powder into a paste, which was then further diluted as specified in the TG318
The observed size distributions confirm the moderate agglomeration at 1 mM Ca, pH7, with NOM. If the particles would have been significantly dissolved, no size distribution would be observable at all by this method, which relies on the detection of the movement of particles during centrifugal separation.
Additionally, the centrifugation methods include a determination of the remaining absorption after centrifugation, fully consistent with the conventional determination of the dissolved fraction after centrifugation as recommended by the TG-318. The remaining absorption was measured at ca. 0.77. This is a fraction of 38% of the initial absorption, which indicates that significant fraction of material have been dissolved at that conditions.
Applicant's summary and conclusion
- Conclusions:
- After 6h, the samples showed high dispersion stability in 0 mM Ca and at any Ca concentration at pH 9. For the samples at all other conditions the stability was intermediate
After 24 hours the stability at pH 9 regardless the Ca concentration remained high. The stability at pH 4 in 1 and 10 mM Ca became low. The stability at all other conditions was intermediate.
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