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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:
Testing was conducted between 15 June 2011 and 20 December 2011.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. The study report was conclusive, done to a valid guideline and the study was conducted under GLP conditions.
Qualifier:
equivalent or similar to
Guideline:
EU Method A.8 (Partition Coefficient)
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
shake-flask method to: flask method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
-4.33
Temp.:
22 °C
pH:
5.1
Details on results:
See any other information on results incl. tables section.

Preliminary estimate

Approximate solubility in n-octanol:        1.10 x 10-2% w/w
Approximate solubility in water    :          61.8% w/w
Approximate Pow  :           1.78 x 10-4
Log10Pow :          

-3.75

Definitive test

The mean peak areas obtained for the standard, stock and sample solutions are shown in the following two tables:

Organic Phase

Solution

Mean Peak Area

Standard 1.08 x 103mg/l

7.280 x 108

Standard 860 mg/l

4.938 x 108

Standard 645 mg/l

3.331 x 108

Standard 662 mg/l

3.132 x 108

Standard 430 mg/l

1.963 x 108

Standard 215 mg/l

6.058 x 107

Standard 108 mg/l

2.366 x 107


  Continued – Organic Phase

Solution

Mean Peak Area

Organic phase matrix blank

0.000

Sample 1

1.100 x 106

Sample 2

1.240 x 106

Sample 3

1.286 x 106

Sample 4

1.729 x 106

Sample 5

1.747 x 106

Sample 6

1.205 x 106

Aqueous Phase

Solution

Mean Peak Area

Standard 1.04 x 103mg/l

5.646 x 108

Standard 833 mg/l

4.196 x 108

Standard 625 mg/l

2.906 x 108

Standard 631 mg/l

3.028 x 108

Standard 416 mg/l

1.743 x 108

Standard 208 mg/l

6.434 x 107

Standard 104 mg/l

2.336 x 107

Aqueous phase matrix blank

0.000

Sample 1

2.803 x 108

Sample 2

2.690 x 108

Sample 3

2.818 x 108

Sample 4

2.697 x 108

Sample 5

2.892 x 108

Sample 6

2.834 x 108

Stock solution A

2.606 x 108

Stock solution B

2.627 x 108

 

Please see attached background material for Calibration Curves.

The total weights (mg) and analysed concentration (mg/l) of the respective phases are shown in the following table:

Sample Number

Total Weight (mg)*

Organic Phase

Aqueous Phase

Analysed Concentration (mg/l)

Weight (mg)†

Analysed Concentration (mg/l)

Weight (mg)†

pH

1

301

0.233

0.121

6.12 x 103

318

5.0

2

371

0.263

0.168

5.92 x 103

379

5.0

3

168

0.240

0.138

6.14 x 103

178

5.1

4

174

0.366

0.217

5.94 x 103

178

5.1

5

98.5

0.370

0.254

6.27 x 103

107

5.1

6

92.7

0.256

0.159

6.17 x 103

98.7

5.1

*From analysis of the stock solution

†From analysis of the respective phase

pH of n-octanol saturated water:  6.3
pH of stock solution:                     5.1
Temperature:                               22.0 ± 0.5°C

The partition coefficient determined for each sample is shown in the following table:

Sample Number

Organic/Aqueous Volume Ratio (nominal)

Partition Coefficient

Log10Pow

Mean Partition Coefficient

1

10:1

3.81 x 10-5

-4.42

4.13 x 10-5

2

4.44 x 10-5

-4.35

3

20:1

3.90 x 10-5

-4.41

5.03 x 10-5

4

6.16 x 10-5

-4.21

5

40:1

5.90 x 10-5

-4.23

5.02 x 10-5

6

4.14 x 10-5

-4.38

Mean Pow : 4.73 x 10-5        log10Pow: -4.33        Pow standard deviation : 1.03 x 10-5

Validation

Recovery of analysis of the sample procedure was assessed and proved adequate for the test.

At a nominal concentration of 0.1 mg/l, a mean percentage recovery of 114% was obtained (range 106 to 120%).

Concentrations have not been corrected for recovery of analysis.



Conclusions:
The partition coefficient of the test item has been determined to be 4.73E-05 at 22.0 ± 0.5°C, log10 Pow, -4.33.
Executive summary:

Determination of partition coefficient was carried out using the shake-flask Method, designed to be compatible with Method A8 Partition Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 107 of the OECD Guidelines for Testing of Chemicals, 27 July 1995.

The partition coefficient of the test item was determined to be 4.73 x 10-5at 22.0 ± 0.5°C (log Pow, -4.33).

Description of key information

The partition coefficient of the test item has been determined to be 4.73 x 10-5 (log Pow, -4.33).

Key value for chemical safety assessment

Log Kow (Log Pow):
-4.33
at the temperature of:
22 °C

Additional information

4.73 x 10-5 , log10 Pow -4.33 at 22.0 ± 0.5°C, using the flask method, designed to be compatible with Method A8 Partition Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 107 of the OECD Guidelines for Testing of Chemicals, 27 July 1995.