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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:
February 08, 2018 - February 16, 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
equivalent or similar to guideline
Guideline:
other: OECD 105
Deviations:
not applicable
Principles of method if other than guideline:
OECD 105
GLP compliance:
no
Type of method:
flask method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
-0.1
Temp.:
20 °C
Remarks on result:
other: pH not determined

Preliminary visual estimation of the n-octanol solubility

Defined amounts of the n-octanol were stirred with increasing volumes of test item at room temperature and visually checked for any undissolved parts.

Table3: Results of the preliminary visual estimation of the n-octanol solubility

Volume of n-octanol / mL

Added amount of test item

/ g

Total amount of test item

/ g

Stirring time

/ min

Appearance of mixture

10

0.0122

0.122

~5

dissolved

0.0971

0.1093

~10

dissolved

0.4620

0.5713

~85

dark blue solution

1.3992

1.9705

~1200

dark blue solution

According to this preliminary test the solubility of the test item in n-octanol was 57.1 - 197.1 g/L (without correction for the purity).

Calculation of the partition coefficient log POW

The partition coefficient POW may be estimated from the saturation concentrations in n-octanol and water. The estimated partition coefficient was calculated with the water solubility data determined in project PS20170184-4 (cS = 123.6 g/L) and the data obtained above. It was calculated to be: log POW -0.3 – 0.2. Also the program KOWWIN (part of EPI Suite) was used for calculating the log POW of the test item. The calculated value was -0.3. Due to the calculations the partition coefficient was estimated based on the ratio of the solubilities in water and octanol. The octanol solubility was determined using the flask method. Shake flask method was not applicable due to the impurity of the test item.


Determination of the solubility in n-octanol: Flask method

The individual saturation solubility of the test item in n-octanol was performed within this study. After that, the partition coefficient was estimated based on the ratio of the test item solubility in n-octanol and water. The flask method was performed as described above. The data for the evaluation are given in Table4. The n-octanol solubility was calculated from the measured and unrounded concentration values and not from the rounded values given in Table4.

Table4: n-Octanol solubility experiments of the test item

Experiment

24 h experiment

48 h experiment

72 h experiment

blank

experiment (72 h)

Amount of test item / mg

10.0

10.0

10.0

--

Amount of octanol / mL

16

16

16

16

Stirring time at 30 °C / h

24

48

72

72

Dilution factor

2500

2500

2500

2500

Measured concentration / mg/L

36.2 / 35.8

36.6 / 36.7

35.4 / 35.0

-- / --

Mean concentration / mg/L

36.0

36.7

35.2

--

n-Octanol solubility / g/L

89.9

91.7

88.1

--

The n-octanol solubility of the test item at 20 °C was determined to be89.89g/L.

Calculation of the partition coefficient log POW from the individual solubilities

In theproject PS20170184-4 the water solubility of the test item at 20 °C was determined to be 123.6 g/L (± 7 g/L). Within this project the n-octanol solubility of the test item at 20 °C was determined to be 89.89 g/L.

The partition coefficient POW of the test item was determined to be: 

log POW = -0.1

Executive summary:

The partition coefficient (n-octanol/water) of the test itemBasic Blue 147 Cl was estimated based on the ratio of the individual solubilities of the test item in water and n-octanol. The solubilities were determined according to the flask method.

It was found to be:

 log POW = -0.1

Description of key information

The partition coefficient (n-octanol/water) of the test itemBasic Blue 147 Cl was estimated based on the ratio of the individual solubilities of the test item in water and n-octanol. The solubilities were determined according to the flask method.

It was found to be:

 log POW =  -0.1

Key value for chemical safety assessment

Log Kow (Log Pow):
-0.1
at the temperature of:
20 °C

Additional information