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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2008-08-05 to 2008-10-03
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Principles of method if other than guideline:
The partition coefficient of the test material was determined over the environmentally relevant pH range of 4 to 10, using the shake-flask method, Method 107 of the OECD Guidelines for Testing of Chemicals, 27 July 1995.
GLP compliance:
yes
Type of method:
shake-flask method to: flask method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
0.015
Temp.:
22 °C
pH:
4.2 - 4.3
Type:
log Pow
Partition coefficient:
-0.021
Temp.:
22 °C
pH:
7 - 7.1
Type:
log Pow
Partition coefficient:
-0.419
Temp.:
22 °C
pH:
9.5 - 9.6

Table 1: pH 4, total weights (mg) and analysed concentration (mg/l) of the respective phases

Sample Number

Volume of water saturated

n-octanol (ml)

Volume of stock solution (ml)

Total Weight (mg)*

Organic Phase

Aqueous Phase

Analysed Concentration (mg/l)

Weight (mg)

Analysed Concentration (mg/l)

Weight (mg)†

pH

1

50

50

9.92

93.0

4.65

85.6

4.28

4.3

2

60

60

11.9

89.4

5.36

86.3

5.18

4.2

3

45

90

17.9

122

5.48

113

10.2

4.3

4

45

90

17.9

121

5.45

112

10.1

4.2

5

100

50

9.92

59.0

5.90

59.7

2.98

4.3

6

110

55

10.9

55.6

6.12

58.9

3.24

4.2

*From analysis of the stock solution

From analysis of the respective phase

Table 2: pH 4, partition coefficient determined for each sample

Sample Number

n-Octanol/Water Volume Ratio

Partition Coefficient

Log10Pow

Mean Partition Coefficient

1

1:1

1.09

3.62 x 10-2

1.06

2

1.04

1.53 x 10-2

3

1:2

1.08

3.20 x 10-2

1.08

4

1.08

3.25 x 10-2

5

2:1

0.989

-4.69 x 10-3

0.967

6

0.945

-2.45 x 10-2

pH 7, total weights (mg) and analysed concentration (mg/l) of the respective phases

Sample Number

Volume of water saturated

n-octanol (ml)

Volume of stock solution (ml)

Total Weight (mg)*

Organic Phase

Aqueous Phase

Analysed Concentration (mg/l)

Weight (mg)

Analysed Concentration (mg/l)

Weight (mg)†

pH

1

50

50

9.80

95.3

4.77

90.4

4.52

7.0

2

60

60

11.8

88.1

5.29

92.0

5.52

7.0

3

45

90

17.6

126

5.69

122

11.0

7.0

4

45

90

17.6

118

5.32

123

11.0

7.0

5

100

50

9.80

58.6

5.86

66.8

3.34

7.1

6

110

55

10.8

57.2

6.29

68.7

3.78

7.0

*From analysis of the stock solution

From analysis of the respective phase

pH 7, partition coefficient determined for each sample

Sample Number

n-Octanol/Water Volume Ratio

Partition Coefficient

Log10Pow

Mean Partition Coefficient

1

1:1

1.05

2.28 x 10-2

1.01

2

0.958

-1.89 x 10-2

3

1:2

1.04

1.50 x 10-2

1.00

4

0.964

-1.59 x 10-2

5

2:1

0.878

-5.67 x 10-2

0.855

6

0.833

-7.95 x 10-2

pH 10, total weights (mg) and analysed concentration (mg/l) of the respective phases

Sample Number

Volume of water saturated

n-octanol (ml)

Volume of stock solution (ml)

Total Weight (mg)*

Organic Phase

Aqueous Phase

Analysed Concentration (mg/l)

Weight (mg)

Analysed Concentration (mg/l)

Weight (mg)†

pH

1

50

50

9.63

53.2

2.66

138

6.89

9.5

2

60

60

11.6

52.7

3.16

138

8.28

9.6

3

45

90

17.3

63.9

2.87

161

14.5

9.6

4

45

90

17.3

63.4

2.86

161

14.5

9.6

5

100

50

9.63

39.4

3.94

108

5.40

9.5

6

110

55

10.6

39.1

4.30

108

5.93

9.6

*From analysis of the stock solution

From analysis of the respective phase

pH 10, partition coefficient determined for each sample

Sample Number

n-Octanol/Water Volume Ratio

Partition Coefficient

Log10Pow

Mean Partition Coefficient

1

1:1

0.386

-0.413

0.384

2

0.382

-0.418

3

1:2

0.396

-0.403

0.395

4

0.395

-0.404

5

2:1

0.365

-0.438

0.364

6

0.363

-0.440

Conclusions:
Log Kow values of 0.015, -0.021 and -0.419 at pH 4, 7 and 10 and 22 were determined for the hydrolysis product in a reliable study conducted according to an appropriate test protocol, and in compliance with GLP.
Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
supporting study
Study period:
2011
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
QSAR prediction
Principles of method if other than guideline:
The result was obtained using an appropriate QSAR method (see attached QMRF and QPRF for details).
Partition coefficient type:
octanol-water
Type:
log Pow
Partition coefficient:
-1.1

Estimated value, no data available for temperature and pH

Conclusions:
An octanol-water partition coefficient value of -1.1 was obtained for the hydrolysis product using an accepted calculation method. The result is considered to be reliable.

Description of key information

Log Kow (phenylsilanetriol): 0.015, -0.021 and -0.419 at pH 4, 7 and 10 and 22°C (measured)

Key value for chemical safety assessment

Log Kow (Log Pow):
-0.021
at the temperature of:
22 °C

Additional information

Measured Log Kow values of 0.015, -0.021 and -0.419 at pH 4, 7 and 10 respectively (at 22°C) were determined for the hydrolysis product (phenylsilanetriol) by the shake-flask method according OECD Guideline 107. A log Kow value of -1.1 was obtained using an appropriate calculation method.