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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:
2019-03-21 to 2019-03-26
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient - Shake Flask Method)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 830.7550 (Partition Coefficient, n-octanol / H2O, Shake Flask Method)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
flask method
Partition coefficient type:
octanol-water
Analytical method:
other: Atomic emission spectrometer
Key result
Type:
Pow
Partition coefficient:
0.3
Temp.:
20 °C
pH:
>= 5.75 - <= 6.35
Key result
Type:
log Pow
Partition coefficient:
-0.36
Temp.:
20 °C
pH:
>= 5.75 - <= 6.35
Details on results:
Partition coefficient of the test item was determined in an n octanol - water two-phase system using the shake-flask method. Based on the measured silicon content in the aqueous phase the Pow of Reaction product of Hexamethylene diisocyanate, oligomers with Mercaptopropyltrimethoxysilane was determined to be 0.46 ± 0.30 (95 % confidence interval) at 20 °C. The log Pow was calculated to be -0.36.

 Measured concentrations

Ratio of solvents
(n-octanol : water)

Concentration in
n-octanol phase
(µg/mL)

Concentration in
aqueous phase
(µg/mL)

pH

1:1

15.4

27.1

6.35

11.5

30.9

6.33

12.4

30.0

6.31

Mean

13.1

29.3

-

RSD%

15

7

-

Mass of test item

0.33 mg

0.73 mg

 

Ratio of solvents
(n-octanol : water)

Concentration in
n-octanol phase
(µg/mL)

Concentration in
aqueous phase
(µg/mL)

pH

2:1

12.9

37.4

6.13

12.0

39.0

6.14

13.2

36.7

6.13

Mean

12.7

37.7

-

RSD%

5

3

-

Mass of test item

0.42 mg

0.64 mg

-

Ratio of solvents
(n-octanol : water)

Concentration in
n-octanol phase
(µg/mL)

Concentration in
aqueous phase
(µg/mL)

pH

1:2

12.6

24.90

5.75

14.4

24.00

5.90

14.8

23.80

5.79

Mean

13.9

24.2

-

RSD%

8

2

-

Mass of test item

0.24 mg

0.82 mg

-

 

Initial quantity of test item = 1.06 mg


 

Calculated partition coefficient (Pow) and log Pow

Ratio of solvents
(n-octanol : water)

Partition coefficient

Log Partition coefficient

Pow

Log Pow

1:1

0.452

-0.35

2:1

0.338

-0.47

1:2

0.576

-0.24

Mean all

0.46

-0.36

95 % Confidence limit

0.30

0.29

 

 

Conclusions:
The log Pow was calculated to be -0.36.
Executive summary:

A study was conducted in accordance with OECD TG 107 and Regulation (EC) No 440/2008 method A.8 to determine the partition coefficient of the test substance using the shake flask method. It was technically not feasible to establish a substance specific method tor the complex test item. Thus, the equilibrium concentration of the test item in both phases was determined by means of ICP. Three tests were carried out using different phase ratio (1:1, 1:2 and 2:1). The entire volume of the two-phase system was 50 mL. Three parallel tests were carried out at all solvent ratios, each. The test vessels were shaken by hand through 180° about its transverse axis a hundred times during five minutes. The separation of the two phases was achieved by centrifugation at 20 °C.The pH values of all water phases were measured.. Based on the measured silicon content in the aqueous phase the Pow of the test iem was determined to be 0.46 ± 0.30 (95 % confidence interval) at 20 °C. The log Pow was calculated to be -0.36 respectively.

Description of key information

The log Pow was calculated to be -0.36.

Key value for chemical safety assessment

Log Kow (Log Pow):
-0.36
at the temperature of:
20 °C

Additional information

A study was conducted in accordance with OECD TG 107 and Regulation (EC) No 440/2008 method A.8 to determine the partition coefficient of the test substance using the shake flask method. It was technically not feasible to establish a substance specific method tor the complex test item. Thus, the equilibrium concentration of the test item in both phases was determined by means of ICP. Three tests were carried out using different phase ratio (1:1, 1:2 and 2:1). The entire volume of the two-phase system was 50 mL. Three parallel tests were carried out at all solvent ratios, each. The test vessels were shaken by hand through 180° about its transverse axis a hundred times during five minutes. The separation of the two phases was achieved by centrifugation at 20 °C.The pH values of all water phases were measured.. Based on the measured silicon content in the aqueous phase the Pow of the test iem was determined to be 0.46 ± 0.30 (95 % confidence interval) at 20 °C. The log Pow was calculated to be -0.36 respectively.

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