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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
calculation (if not (Q)SAR)
Adequacy of study:
key study
Study period:
August 16, 2017
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
Qualifier:
equivalent or similar to guideline
Guideline:
EU Method A.8 (Partition Coefficient - Shake Flask Method)
Version / remarks:
as per calculation method which is specified in EU A.8 as well as OECD 107
Deviations:
no
Principles of method if other than guideline:
The log Kow value was determined by calculation method based on solubility in n-octanol and water.
GLP compliance:
not specified
Type of method:
estimation method (solubility ratio)
Remarks:
octanol solubility was divided by the water solubility
Partition coefficient type:
octanol-water
Key result
Type:
log Pow
Partition coefficient:
ca. 0.25
Remarks on result:
other: calculated based on solubility ratio in n-octanol and water
Details on results:
The octanol solubility is determined to be 517 g/L mixture. The aqueous solubility is determined to 291 g/L mixture.

Pow = 517 g/L / 291 g/L = 1.78
Log Pow = 0.25

Water solubility:

A study was conducted to determine the water solubility of the solvent free form of the test substance, Oleyl TMAC (91.9% active), using the preliminary test according to OECD Guideline 105. The substance was mixed with MilliQ water at different ratios in order to determine the water solubility, at pH 8 and 20 °C. It wasassumed that there are no changes in volume when mixing water and substance. Uptil a weight ratio of 30:70 (substance:water) [%], a clear and homogeneous mixture was obtained. However, at a ratio of 35:65 [%] a clear and homogeneous mixture was not obtained, thus at this ratio the substance is not fully soluble in water. Using the density value of of 0.9 g/cm3, water solubility was determined by dividing the weight of the dissolved substance with the totoal volume of the mixture. A weight of 0.2918 g of the test substance was determined to have a volume of 0.3242 cm3; and 0.6782 g MilliQ water had a volume of 0.6782 cm3. The total volume was calculated to be 1.0024 cm3. Under the study conditions, the water solubility of the test substance, was determined to be 291 g/L mixture (Linda, 2017).

n-octanol solubility:

A study was conducted to determine the octanol solubility of the solvent free test substance, Oleyl TMAC (91.9% active), by a visual screening test similar to the preliminary test in OECD 105 Guideline.The test substance has been mixed with 1-octanol saturated with Milli-Q water using slow-stirring conditions for at least 24 h, at different ratios in order to determine the octanol solubility. It is assumed that there are no changes in volume when mixing 1-octanol with the test substance. The density of 1–octanol, 0.825 g/mL at 20 °C was used in the calculations. At a weight ratio of 55:45 (substance:octanol) [%] a clear and homogeneous mixture is obtained. However, at a weight ratio of 60:40 [%] a clear and homogeneous mixture is not obtained, thus at this ratio the substance is not fully soluble in octanol. The pH of the solutions is close to 5 and the temperature is 20 °C. The density of the substance is taken from test facility study no. 515667, “Determination of Physico-Chemical Properties of Oleyltrimethylammonium chloride (dried)”. The octanol solubility was calculated as the weight of the dissolved substance divided by the volume of the mixture. Under the study conditions, the octanol solubility of the test substance (solvent free) is determined to be 517 g/L mixture at 20 °C and pH 5 (Linda, 2017).

Conclusions:
Under the study conditions, the log Pow of the solvent free test substance was calculated to be 0.25.
Executive summary:

A study was conducted to determine the partition coefficient of the test substance, Oleyl TMAC (91.9% active), by dividing the octanol solubility by the water solubility as per the method mentioned in the OECD Guideline 107 and EU Method A.8. It is assumed that there are no changes in volume when mixing water or octanol with the test substance. The octanol solubility and CMC based water solubility values of the test substance were determined to be 517 g/L (Linda, 2017) at 20 deg C and pH 5 and 291 g/L at room temperature (Linda, 2017) respectively. Under the study conditions the log Pow of the solvent free test substance was calculated to be 0.25 (Linda, 2017).

Description of key information

The partition coefficient of the test substance was determined by dividing the octanol solubility by the water solubility as per the method mentioned in OECD Guideline 107 and EU Method A.8 (Wiman, 2017).

Key value for chemical safety assessment

Log Kow (Log Pow):
3.25
at the temperature of:
20 °C

Additional information

(calculated based on individual solubility)