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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:
22 September to 15 November 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)
GLP compliance:
yes (incl. certificate)
Remarks:
Federal Office for the Environment (FOEN)
Type of method:
slow-stirring method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
5.99
Temp.:
25 °C
Remarks on result:
other: pH is not reported

Results

Thermostated glass flasks containing the aqueous phase and n-octanol were slowly stirred, after dosing the test item dissolved in octanol, until equilibrium distribution of the test item between the two phases was achieved. The temperature was kept constant at 25 °C ± 1 °C. The concentration of the test item in the phases was measured by HPLC/UV. The partition coefficient (n-octanol/water) log Pow was calculated. The equilibrium distribution was defined to be achieved, when four sampling intervals separated by at least 5 hours yielded similar log Pow values, expressed by a plateau with zero slope. The testing was performed in triplicate.

The results of the individual measurements of the slow-stirring test and the calculation of the log Pow values are given in the table below.

 

Slow-Stirring Test - Results obtained for log Pow.The tabulated values of the samples represent rounded results obtained by calculation using the exact data.

Stirring

Time

[hours]

Measured Concentration in n-

Octanol

[μg/L]

Measured

Concentration in

Water

[μg/L]

Log Pow

 

Test 1

Test 2

Test 3

Test 1

Test 2

Test 3

Test 1

Test 2

Test 3

mean

168

20961179

20525802

21014367

11.1

16.3

17.8

6.28

6.1

6.07

6.15

173

22206444

22625919

20681529

18.8

25.2

32.8

6.07

5.95

5.8

5.94

192

19810775

20643146

22907214

18.4

24.2

31.5

6.03

5.93

5.86

5.94

197

17405237

21014916

21071394

18.3

24.7

32

5.98

5.93

5.82

5.91

Means:

6.09

5.98

5.89

5.99

Overall mean

5.99

± 0.10

(1.7%

RSD)

 

Conclusions:
A log Pow of 5.99 ± 0.10 at 25°C was determined for the test substance according to OECD 123.

Description of key information

Log Pow: 5.99 ± 0.10 at 25°C (OECD 123, Slow-Stirring Method)

Key value for chemical safety assessment

Log Kow (Log Pow):
5.99
at the temperature of:
25 °C

Additional information