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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:
2007-03-19 to 2007-06-20
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient)
Version / remarks:
EEC Publication no. L383, December 29, 1992
Deviations:
yes
Remarks:
see "Principles of method if other than guideline"
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Version / remarks:
April 13, 2004
Deviations:
yes
Remarks:
see "Principles of method if other than guideline"
Principles of method if other than guideline:
According to guidelines, the determination of the Pow of the test substance should be performed in its non-ionised form. Therefore, the pKa values of the test substance were calculated using Perrin calculation method (pKalc 5.0, module in Pallas 3.0, CompuDrug International). These calculations show that there is not a pH at which all ionisable groups are in their non-ionised form. At pH 2, net charge of the test substance is zero and therfore it was descided to perform a test at this pH. However, this pH was not in the environmentally relevant range of pH 5.0-9.0. Thus, an additional test was performed at neutral pH. Under these conditions, the net charge will deviate from zero.
GLP compliance:
yes (incl. certificate)
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
1.1
Temp.:
22 °C
pH:
7
Remarks on result:
other: weighted mean
Type:
log Pow
Partition coefficient:
< 0.3
Temp.:
22 °C
pH:
7
Remarks on result:
other: component 1, 52% area
Type:
log Pow
Partition coefficient:
>= 1.1 - <= 2.8
Temp.:
22 °C
pH:
7
Remarks on result:
other: component 2, 46% area
Type:
log Pow
Partition coefficient:
4.1
Temp.:
22 °C
pH:
7
Remarks on result:
other: component 3, 1.1% area

In the chromatogram of the test substance solution, several test substance peaks were observed. Some peaks were broad indicating not pure reversed phase retention as required for accurate determination of Kow. Because a different method to determine Kow is not applicable, the Pow of these peaks were reported as a range.

 

 

Test substance peak

pH

log Kow

Peak area [%]

Component 1

2

<0.3

28

Component 2

2

2.7

23

Component 3

2

2.9 – 4.0

48

Component 4

2

4.2

1.7

Component 1

7

<0.3

52

Component 2

7

1.1 – 2.8

46

Component 3

7

4.1

1.1

 

 

 

Conclusions:
The log Pow of Amphopropionate C8 is in the range of < 0.3 to 4.0 at pH 2.0 and < 0.3 to 4.1 at pH 7.0.
Executive summary:

The n-octanol/water partition coefficient of Amphopropionate C8 was determined according to OECD Guideline 117 (13 April 2004) and EU Method A.8 (29 December 1992) using the HPLC method. According to guidelines, the determination of the Pow of the test substance should be performed in its non-ionised form. Therefore, the pKa values of the test substance were calculated using Perrin calculation method (pKalc 5.0, module in Pallas 3.0, CompuDrug International). These calculations show that there is not a pH at which all ionisable groups are in their non-ionised form. At pH 2, net charge of of the test substance is zero and, thus, the test was performed at this pH. However, because this pH was not in the environmentally relevant range of pH 5.0-9.0, an additional test was performed at neutral pH. Under these conditions, the net charge will deviate from zero.

In the chromatograms of the test substance solutions, several test substance peaks were observed. Some peaks were broad indicating not pure reverse phase retention as required for accurate determination of Pow. Because a different method to determine Pow is not applicable, these values were reported as a range. The log Pow of Amphopropionate C8 is, for the different components, in the range of < 0.3 to 4.0 at pH 2.0 and < 0.3 to 4.1 at pH 7.0.

Description of key information

< 0.3 to 4.0 at pH 2.0 and < 0.3 to 4.1 at pH 7.0 for the different compounds; weighted mean: 1.1 (OECD TG 117 / EU method A.8; RL1; GLP)

Key value for chemical safety assessment

Log Kow (Log Pow):
1.1
at the temperature of:
22 °C

Additional information

The n-octanol/water partition coefficient of Amphopropionate C8 was determined according to OECD Guideline 117 (13 April 2004) and EU Method A.8 (29 December 1992) using the HPLC method. According to guidelines, the determination of the Pow of the test substance should be performed in its non-ionised form. Therefore, the pKa values of the test substance were calculated using Perrin calculation method (pKalc 5.0, module in Pallas 3.0, CompuDrug International). These calculations show that there is not a pH at which all ionisable groups are in their non-ionised form. At pH 2, net charge of of the test substance is zero and, thus, the test was performed at this pH. However, because this pH was not in the environmentally relevant range of pH 5.0-9.0, an additional test was performed at neutral pH. Under these conditions, the net charge will deviate from zero.

In the chromatograms of the test substance solutions, several test substance peaks were observed. Some peaks were broad indicating not pure reverse phase retention as required for accurate determination of Pow. Because a different method to determine Pow is not applicable, these values were reported as a range. The log Pow of Amphopropionate C8 is, for the different components, in the range of < 0.3 to 4.0 at pH 2.0 and < 0.3 to 4.1 at pH 7.0.

A weighted average mean value of 1.1 was calculated based on the respective peak area percentages.