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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
19 March 2015 - 05 September 2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose for cross-reference:
reference to other study
Reason / purpose for cross-reference:
reference to other study
Reason / purpose for cross-reference:
reference to other study
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient)
Version / remarks:
(2008)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Version / remarks:
(1995)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 830.7550 (Partition Coefficient, n-octanol / H2O, Shake Flask Method)
Version / remarks:
(1996)
Deviations:
no
GLP compliance:
yes
Type of method:
estimation method (solubility ratio)
Partition coefficient type:
octanol-water
Analytical method:
other: SEC-ELSD
Type:
Pow
Partition coefficient:
> 16.1
Temp.:
20 °C
Remarks on result:
other: Estimated from the n-octanol (>1 kg/L) and the water solubility (62.1 g/L)
Key result
Type:
log Pow
Partition coefficient:
> 1.2
Temp.:
20 °C
Remarks on result:
other: Estimated from the n-octanol (>1 kg/L) and the water solubility (62.1 g/L)
Details on results:
FIRST SHAKE FLASK METHOD:
- The analysed concentration of the stock solution was 21.7 g/L.
- The nominal quantity in each test sample was 43.3 mg.
- The quantity analysed in each test sample ranged from 21.3 mg to 27.2 mg; recovery ranged from 49% to 63%
- No test substance was detected in the pretreated phases from the blank test sample
- After centrifugation, a white layer was observed between the 2 phases
- Based on the low recovery and the presence of a white layer between both phases, it was concluded that the results of the first shake-flask method are not reliable.

SECOND SHAKE FLASK METHOD:
- The response of the test substance in the n-octanol samples and 4 out of 6 water samples was below the lowest calibration standard. Quantification of the samples could not be performed.
- The analysed concentration of the stock solution was 7.24 g/L. It demonstrated that the test was performed at least at a two-times lower concentration level than the first shake flask method.
- Similarly to the first test, a white layer between the 2 phases was observed in the centrifuged samples.
- Testing at lower test levels was not possible, as the analytical method is not sensitive enough.
- It was concluded that the shake-flask method is not applicable to this substance

ESTIMATION METHOD:
- After the stirring period, the test mixture at a 1:1 (w/w) ratio was clear and no undissolved test item was observed.
- From this, it was concluded that the n-octanol solubility of the test substance at 20°C was >1 kg/L.
- The Pow is calculated from the n-octanol and water solubilities to be >16.1, corresponding with a log Pow of >1.2.
Conclusions:
In a GLP-compliant study in accordance with EC A.8 and OECD 107, the shake-flask method was found to be not applicable to this substance. The log Pow of the substance was estimated from the quotient of the n-octanol solubility and the water solubility to be >1.2.

Description of key information

The log Pow of the substance was estimated from the quotient of the n-octanol solubility and the water solubility to be >1.2 at 20 °C.

Key value for chemical safety assessment

Additional information

Key value for chemical safety assessment: >1.2 at 20 °C

Determined in a GLP-compliant study in accordance with EC A.8 and OECD 107 (estimation method).