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Physical & Chemical properties

Partition coefficient

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Administrative data

Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
between 10 February 2009 and 02 April 2009.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: 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 relevant results.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
Date of inspection: 19/08/08 Date of Signature: 04/03/09
Type of method:
shake-flask method to: flask method
Partition coefficient type:
octanol-water

Test material

Reference
Name:
Unnamed
Type:
Constituent

Study design

Analytical method:
high-performance liquid chromatography

Results and discussion

Partition coefficientopen allclose all
Type:
Pow
Partition coefficient:
0.028
Temp.:
22.1 °C
pH:
>= 7.3 - <= 7.5
Type:
log Pow
Partition coefficient:
-1.56
Temp.:
22.1 °C
pH:
>= 7.3 - <= 7.5
Details on results:
Preliminary estimate:
Approximate solubility in n-octanol: <0.124 g/l
Approximate solubility in water: >19.0 g/l
Approximate Pow: <6.51 x 10-3
Log10 Pow: <-2.19

Any other information on results incl. tables

 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 Area

Standard 10.0 mg/l

1.302 x 106

Standard 10.2 mg/l

1.376 x 106

Organic phase matrix blank

0.000

Sample 1

4.949 x 106

Sample 2

4.750 x 106

Sample 4

4.492 x 106

Sample 5

4.815 x 106

Sample 6

4.814 x 106

Aqueous Phase

Solution

Mean Area

Standard 251 mg/l

3.263 x 107

Standard 257 mg/l

3.404 x 107

Aqueous phase matrix blank

0.000

Sample 1

3.405 x 107

Sample 2

3.408 x 107

Sample 4

3.299 x 107

Sample 5

3.432 x 107

Sample 6

3.404 x 107

Stock solution A

3.492 x 107

Stock solution B

3.439 x 107

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

87.2

74.7

2.46

2.60 x 103

85.6

7.3

2

92.4

71.7

2.51

2.60 x 103

90.9

7.3

4

68.7

67.8

3.52

2.51 x 103

65.4

7.5

5

116

72.6

1.60

2.62 x 103

115

7.4

6

137

72.6

1.89

2.59 x 103

135

7.3

pH of n-octanol saturated water:    7.3
pH of stock solution:            7.3
Temperature:                         22.1 ± 0.5°C


*From analysis of the stock solution

†From analysis of the respective phase

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

Sample Number

Organic/Aqueous Volume Ratio

Partition Coefficient

Log10Pow

Mean Partition Coefficient

1

1:1

2.88 x 10-2

-1.54

2.82 x 10-2

2

2.76 x 10-2

-1.56

4

2:1

2.70 x 10-2

-1.57

2.70 x 10-2

5

1:2

2.78 x 10-2

-1.56

2.79 x 10-2

6

2.80 x 10-2

-1.55

Mean Pow : 2.78 x 10-2        log10Pow: -1.56        Powstandard deviation : 6.61 x 10-4

Validation:

Linearities of the detector response with respect to concentration were assessed over the nominal concentration ranges of 0 to 100 mg/l for the organic phase and 0 to 500 mg/l for the aqueous phase. These were satisfactory with first order correlation coefficients of 1.000 and 0.998 obtained for the organic and aqueous phases respectively.

Discussion:

Substances having a log10Pow of greater than 3 are regarded as having the potential to bioaccumulate in the environment.

Testing was performed without any pH adjustment to the aqueous phase. Testing by the flask method at neutral pH is the preferred choice for test items that are salts. The pH of the unadjusted n-octanol saturated water and stock solutions were approximately pH 7.

Although sample 3 was abandoned during testing, it was not considered appropriate to repeat the test using a single flask at the required ratio. Results obtained in the definitive test showed consistency between all 5 samples and as such, additional testing would be anticipated to yield no further useful information.

Applicant's summary and conclusion

Conclusions:
The partition coefficient of the test item, Sodium Octanoyl Isethionate, has been determined to be 2.78 x 10-2, log10 Pow, -1.56.
Executive summary:

Partition Coefficient:

The partition coefficient of the Sodium Octanoyl Isethionate test item, Sample Number S2952201 has been determined to be 2.78 x 10-2at 22.1 ± 0.5°C, log10Pow-1.56, using the shake-flaskthod, Method A8 Partition Coefficient of Commission Regulation (EC) No 440/2008 of 30 May 2008.