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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:
03 September 2014 to 16 November 2014
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Version / remarks:
2004
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient - HPLC Method)
Version / remarks:
2008
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
HPLC method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
1.67
Temp.:
40 °C
pH:
10.5
Type:
Pow
Partition coefficient:
47.1
Temp.:
40 °C
pH:
10.5
Key result
Type:
Pow
Partition coefficient:
2.8
Temp.:
40 °C
pH:
7
Remarks on result:
other: Corrected value
Key result
Type:
log Pow
Partition coefficient:
0.446
Temp.:
40 °C
pH:
7
Remarks on result:
other: Corrected value
Details on results:
Preliminary Estimate: Estimated log10 Pow: -0.68

DEFINITIVE TEST
Calibration
The retention times of the dead time and the retention times, capacity factors and log10 Pow values for the reference standards were:
- Formamide: mean retention time = 1.562 mins
- 2-Butanone: mean retention time = 2.120 mins, capacity factor (k’) = 0.357, Log10 Pow = 0.3
- Aniline: mean retention time = 2.527 mins 0.618, capacity factor (k’) = -0.209, Log10 Pow = 0.9
- Benzyl Alcohol: mean retention time = 2.963 mins, capacity factor (k’) = 0.896, Log10 Pow = 1.1
- Benzonitrile: mean retention time = 4.262 mins, capacity factor (k’) = 1.728, Log10 Pow = 1.6
- Benzene: mean retention time = 8.503 mins, capacity factor (k’) = 4.442, Log10 Pow = 2.1
- Toluene: mean retention time = 17.989 mins, capacity factor (k’) = 10.514, Log10 Pow = 2.7

Partition coefficient of sample
The retention times, capacity factor and log10 P ow value determined for the sample are:
- Retention time (mins) = 5.069 (injection 1) and 4.925 (injection 2)
- Capacity factor (k’) = 2.244 (injection 1) and 2.152 (injection 2)
- Log10 k’ = 0.351 (injection 1) and 0.333 (injection 2)
- Log10 Pow = 1.69 (injection 1) and 1.66 (injection 2)
- Mean log10 Pow: 1.67
- Partition coefficient: 47.1

Discussion

- The HPLC method was preferred based on the necessity to minimise exposure of the test material to the atmosphere.

- The mobile phase was adjusted to pH 10.6 to ensure the test material was tested in its non-ionised form.

- The chromatography of the test material showed one main peak with a well-defined and reproducible retention time. The HPLC method was therefore considered to be suitable for the purpose of the study.

- The test material has a highest predicted dissociation constant of 8.2 ± 0.5 using ACD/Labs I-Lab 2.0 - ilab.acdlabs.com, algorithm version: v5.0.0.184. As testing was carried out at pH 10.6, a correction was made to obtain an estimated log10 Pow value for the test material at an environmentally relevant pH, i.e. pH 7. The corrected log10 Pow was calculated using:

P’ow = (Pow / 1+10^(pKa-pH))

P'ow = corrected partition coefficient

Pow = HPLC estimated partition coefficient

pKa = 8.2

pH = 7

- The test material has a corrected partition coefficient of 2.80, log10 P'ow 0.446 at pH 7.

Conclusions:
Under the conditions of this study, the partition coefficient of the test material has been determined to be 47.1, log10 Pow 1.67. The test material has a corrected partition coefficient of 2.80, log10 P'ow 0.446 at pH 7.
Executive summary:

The partition coefficient of the test material was investigated in accordance with the standardised guidelines OECD 117 and EU Method A.8., under GLP conditions.

The HPLC method was preferred based on the necessity to minimise exposure of the test material to the atmosphere. The mobile phase was adjusted to pH 10.6 to ensure the test material was tested in its non-ionised form. The chromatography of the test material showed one main peak with a well-defined and reproducible retention time. The HPLC method was therefore considered to be suitable for the purpose of the study.

The test material has a highest predicted dissociation constant of 8.2 ± 0.5 using ACD/Labs I-Lab 2.0 - ilab.acdlabs.com, algorithm version: v5.0.0.184. As testing was carried out at pH 10.6, a correction was made to obtain an estimated log10 Pow value for the test material at an environmentally relevant pH, i.e. pH 7.

Under the conditions of this study, the partition coefficient of the test material has been determined to be 47.1, log10 Pow 1.67. The test material has a corrected partition coefficient of 2.80, log10 P'ow 0.446 at pH 7.

Description of key information

Under the conditions of this study, the partition coefficient of the test material has been determined to be 47.1, log10 Pow 1.67. The test material has a corrected partition coefficient of 2.80, log10 P'ow 0.446 at pH 7.

Key value for chemical safety assessment

Log Kow (Log Pow):
0.446
at the temperature of:
40 °C

Additional information

The partition coefficient of the test material was investigated in accordance with the standardised guidelines OECD 117 and EU Method A.8., under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

The HPLC method was preferred based on the necessity to minimise exposure of the test material to the atmosphere. The mobile phase was adjusted to pH 10.6 to ensure the test material was tested in its non-ionised form. The chromatography of the test material showed one main peak with a well-defined and reproducible retention time. The HPLC method was therefore considered to be suitable for the purpose of the study.

The test material has a highest predicted dissociation constant of 8.2 ± 0.5 using ACD/Labs I-Lab 2.0 - ilab.acdlabs.com, algorithm version: v5.0.0.184. As testing was carried out at pH 10.6, a correction was made to obtain an estimated log10 Pow value for the test material at an environmentally relevant pH, i.e. pH 7.

Under the conditions of this study, the partition coefficient of the test material has been determined to be 47.1, log10 Pow 1.67. The test material has a corrected partition coefficient of 2.80, log10 P'ow 0.446 at pH 7.