Registration Dossier

Physical & Chemical properties

Partition coefficient

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
06 Jan - 24 Jan 2017
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Partition coefficient of the test item was calculated based on the ratio of its water solubility and its octanol solubility (based on OECD 105).
Reference:
Composition 0
Qualifier:
equivalent or similar to
Guideline:
other: Based on determination of ratio n-octanol solubility vs. aqueous solubility. Solubility determination accordingto OECD guideline 105, determination of octanol solubility based on principle of OECD guideline 105.
Qualifier:
according to
Guideline:
other: EU method A.8.
GLP compliance:
no
Type of method:
calculation method (fragments)
Partition coefficient type:
octanol-water
Test material information:
Composition 1
Specific details on test material used for the study:
Storage conditions: ambient temperature (10 to 30 °C)
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
-4.9
Temp.:
20 °C
Remarks on result:
other: pH not measured

 

Results
Table 1 – Preliminary visual estimation of n-octanol solubility

Amount of test item [mg]

Added volume of n-octanol [mL]

Total volume of n-octanol [mL]

Stirring time [h]

Appearance of mixture

22.5

2

2

0.5

Not dissolved

8

10

0.5

90

100

2

Very turbid

 

The solubility of the test item in n-octanol was: csn-octanol< 225 mg/L.

Calculation of Partition Coefficient from Preliminary Test
The calculation was done with the result of the preliminary estimation of water solubility determined in the study report reference [4.8 -1], i.e. cswater= 77 g/L and the csn-octanolvalue above.

It was calculated to be: log POW< -2.5

Using KOWWIN, the calculated value was -0.1.

Due to the calculations the partition coefficient was determined based on the ratio of the individual solubilities the test item in water and octanol. The individual octanol solubility was determined using the flask method. The shake flask method and HPLC method were not applicable due to the low log POW.

Determination of solubility in n-octanol – Flask Method
The n-octanol solubility was calculated from the measured and unrounded concentration values (not from the rounded values given in table 2).

Table 2 – n-octanol Solubility Experiments of the Test Item

Experiment

72 h experiment

96 h experiment

120 h experiment

Blank experiment (120 h)

Test item amount [mg]

67.9

67.9

76.0

--

Octanol amount [mL]

50

Stirring time at 30 °C [h]

72

96

120

120

Aliquot of the flasks [mL]

10

Volume of the aqueous phase used for the extraction [mL]

3

Dilution factor

0.4

Measured concentration [mg/L]

2.58
2.64

2.63
2.64

1.31
1.35

--
--

Mean concentration [mg/L]

2.61

2.63

1.33

--

n-octanol solubility [mg/L]

1.04

1.05

0.53

--

 

In a first test series with shorter stirring times, the results of the 3 experiments were in the same order of magnitude as in the reported second test series but they showed a larger variation. Thus the test series was repeated (see Table 2). It is  likely that the result of the 120 h stirring time experiment is an outlier. As a conservative approach, the highest n-octanol solubility was taken as a final result.

The n-octanol solubility of the test item at 20 °C was determined to be 1.1 mg/L.

Calculation of Partition Coefficient from Individual Solubilities
In the study report 20160198.05, the water solubility of the test item at 20 °C was cswater= 77 g/L. In this project, the n-octanol solubility of the test item at 20 °C was csn-octanol= 1.1 mg/L. Thus, the partition coefficient was calculated to be:

log POW = -4.9

Description of key information

log POW = -4.9 at 20 °C (Calculation, EU Method A.8.)

Key value for chemical safety assessment

Log Kow (Log Pow):
-4.9
at the temperature of:
20 °C

Additional information

Partition coefficient was determined based on the ratio of the individual solubilities of the test item in water and octanol. The individual octanol solubility was determined using the flask method. The shake flask method and HPLC method were not applicable due to the low log POW.