Registration Dossier

Physical & Chemical properties

Partition coefficient

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Followed guideline and GLP requirements.
Reference:
Composition 1
Qualifier:
according to
Guideline:
EPA OPPTS 830.7550 (Partition Coefficient, n-octanol / H2O, Shake Flask Method)
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient)
GLP compliance:
yes (incl. certificate)
Type of method:
shake-flask method to: flask method
Partition coefficient type:
octanol-water
Test material information:
Composition 1
Analytical method:
gas chromatography
Type:
Pow
Partition coefficient:
>= 125
Temp.:
22 °C
pH:
ca. 9
Remarks on result:
other: Pow standard deviation 14.7
Type:
log Pow
Partition coefficient:
ca. 2.1
Temp.:
22 °C
pH:
ca. 9

Total Weights and Analyzed Concentrations of Respective Phases

Sample number

Total Weight (mg)*

Organic Phase Analyzed Concentration (x 103mg/l)

Organic Phase Weight (mg)#

Aqueous Phase Analyzed Concentration (mg/l)

Aqueous Phase Weight (mg)#

pH

1

176

2.48

174

21.0

1.47

9.1

2

150

2.47

148

21.0

1.26

9.1

3

105

2.47

104

23.6

1.99

9.1

4

113

2.50

112

18.2

1.64

9.1

5

75

2.39

71.8

16.5

1.98

9.1

6

55

2.43

53.4

19.1

1.68

9.1

pH of pH 9 buffered n-octanol saturated water 9.0

Temperature 22.0 +/- 0.5 degrees C

* From analysis of stock solution        # From analysis of respective phase

Partition coefficient determined for each sample

Sample Number

Organic/Aqueous Volume Ratio

Partition coefficient

Log10Pow

Mean Partition Coefficient

1

1.1

118

2.07

118

2

1.1

117

2.07

118

3

1.2

105

2.02

121

4

1.2

137

2.14

121

5

1.4

145

2.16

136

6

1.4

127

2.10

136

Mean Pow= 1.25      Standard Deviation = 14.7     Log10Pow = 2.10

Conclusions:
In a shake-flask n-octanol partition coefficient test, test article mean Pow was 125 (SD 14.7) with log Pow 2.10
Executive summary:

A partition coefficient value of 125 at 22.0 degrees C +/- 0.5, and log10Pow 2.10 was determined for the test article using the shake-flask method (Method A8 Partition Coefficient of Commission Regulation (EC) No. 440/2008 of 30 May 2008 and Method 830.7550 of the OPPTS Guideline). 

In conducting the test, the n-octanol saturated water was buffered to pH 9 to ensure the test material was partitioned in the least ionized form possible within the environmentally relevant pH range of 5 to 9. The dissociation constants of the two amine groups were estimated to be 10.91 +/- 0.29 and 11.56 +/- 0.29 (ACD/l-lab Web Service, ACD/pKa 8.03). Due to a pH of at least 13 being required to give the un-ionized molecule, it was considered impractical to perform the test at such a high pH as well as exceeding the environmentally relevant range.

Substances having a and log10Pow2.10 of greater than 3 are regarded as having the potential to bioaccumulate in the environment, but as the overall test result was log10Pow2.10, this suggests that the test article is not a bioaccumulation risk. In addition, the partition coefficient is anticipated to decrease further at neutral and weakly acidic pH’s as the degree of ionization will increase. Although the preliminary estimate of partition coefficient based on visual solubilities resulted in a log value greater than 3, this value was believed to be artificially high due to the miscibility of the test material in n-octanol. As the method guidelines limit the maximum stock concentration at 0.01 M, such a value could not be achieved for a definitive test with the constraints of the guidelines. 

Description of key information

The partition coefficient of the test article was determined by using the shake-flask method (Method A8 Partition Coefficient of Commission Regulation (EC) No. 440/2008 of 30 May 2008 and Method 830.7550 of the OPPTS Guideline). The partition coefficient value (Kow) of the test article was estimated at 125 at 22.0°C =/-0.5 (LogKow = 2.10). The current value suggests that the test article do not display any bioaccumulation risk. In addition, the partition coefficient is anticipated to decrease further at neutral and weakly acidic pH’s as the degree of ionization will increase.

Key value for chemical safety assessment

Log Kow (Log Pow):
2.1
at the temperature of:
22 °C

Additional information