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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:
From 18 July, 2011 to 26 April, 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient)
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
no
GLP compliance:
yes
Type of method:
shake-flask method to: flask method
Partition coefficient type:
octanol-water
Analytical method:
other: HPLC-MS
Key result
Type:
log Pow
Partition coefficient:
-0.13
Temp.:
20 °C
Remarks on result:
other: based on solubility in n-octanol/distilled water
Key result
Type:
log Pow
Partition coefficient:
-0.13
Temp.:
20 °C
Remarks on result:
other: based on solubility in n-octanol/buffer solutions
Key result
Type:
log Pow
Partition coefficient:
2.39
Temp.:
20 °C
Remarks on result:
other: based on solubility in n-octanol/critical micelle concentrations
Details on results:
The n-octanol solubility of the test substance as the sum of the solubilities of C8-TMAC, C10-TMAC, C12-TMAC, C14-TMAC, C16-TMAC, C18-TMAC and C18:1-TMAC was 243 g/L (determined at 20.4±0.6°C). According to information supplied by the sponsor, the solubility of the test substance in distilled water and in buffer solutions was 328 g/L (determined at 20.0°C) and the critical micelle concentration is 1 g/L (determined at 20.0 ± 0.1°C).

Hence, the partition coefficients calculated using these solubility values are:
- Based on solubility in distilled water: Pow = 0.74; log Pow = -0.13
- Based on solubility in buffer solutions: Pow = 0.74; log Pow = -0.13
- Based on critical micelle concentration: Pow = 243; log Pow = 2.39
Conclusions:
Under the test conditions, the partition coefficient of the substance was calculated to be -0.13, -0.13 and 2.39 at 20°C the quotient of the n-octanol/distilled water, n-octanol/buffer solutions and n-octanol/critical micelle concentrations respectively.
Executive summary:

A study was conducted to calculate the partition coefficient of the test substance, Coco TMAC using the quotient of the n-octanol solubility and the water solubility, according to OECD 107 and EU A.8 guidelines, in compliance with GLP. The n-octanol solubility of the substance as the sum of the solubilities of C8-TMAC, C10-TMAC, C12-TMAC, C14-TMAC, C16-TMAC, C18-TMAC and C18:1-TMAC was determined to be 243 g/L (at 20.4±0.6°C). The solubility of the substance in distilled water and in buffer solutions was 328 g/L (determined at 20.0°C) and the critical micelle concentration was 1 g/L (determined at 20.0 ± 0.1°C).Therefore, the partition coefficient of the substance was calculated to be -0.13, -0.13 and 2.39 at 20°C the quotient of the n-octanol/distilled water, n-octanol/buffer solutions and n-octanol/critical micelle concentrations respectively (Brekelmans, 2012).

Description of key information

Under the test conditions, the partition coefficient of the substance was calculated to be -0.13, -0.13 and 2.39 at 20°C the quotient of the n-octanol/distilled water, n-octanol/buffer solutions and n-octanol/critical micelle concentrations respectively.

Key value for chemical safety assessment

Log Kow (Log Pow):
2.39
at the temperature of:
20 °C

Additional information

The partition coefficient was calculated using the ratio of the n-octanol solubility and the water solubility (critical micelle concentration (CMC)) according to OECD Guideline 107 and EU Method A.8 (Brekelmans, 2012).