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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:
18-07-2013 to 05-09-2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study performed under GLP. All relevant validity criteria were met.
Qualifier:
according to guideline
Guideline:
OECD Guideline 123 (Partition Coefficient (1-Octanol / Water), Slow-Stirring Method)
Deviations:
no
Qualifier:
equivalent or similar to guideline
Guideline:
EU Method A.23 Partition Coefficient (1-Octanol/Water): Slow-Stirring Method
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
inspected: July 2012 ; signature: November 2012
Type of method:
slow-stirring method
Partition coefficient type:
octanol-water
Analytical method:
gas chromatography
Type:
log Pow
Partition coefficient:
>= 4.23 - <= 4.29
Temp.:
25 °C
pH:
6.4
Remarks on result:
other: basis of two (n=2) constituent peaks with peak area > 10%
Conclusions:
The octanol / water partition coefficient was determined to be log Pow = 4.23 to 4.29 at 25 ± 0.5 °C and pH 6.4.
Executive summary:

The octanol / water partition coefficient was determined to be log Pow = 4.23 to 4.29 at 25 ± 0.5 °C and pH 6.4. The partition coefficient of the substance was determined according to OECD TG 123 slow stirring method under GLP, at 25 ± 0.5 °C from three independent replicates (test vessels) with four utilised out of seven sub-replicates (samples). Three sub-replicates were excluded due to problems with sample treatment and not utilised in further calculations. The pH-value of the aqueous phases was determined by a pH-meter. The pH of the aqueous phase at t=147 hours equilibration (before) was pH: 7.1 to 7.3 in all replicates and at t=478 hours equilibration (after) was pH: 6.4 – 6.5. Analytical evaluation was performed using GC-FID on a capillary analytical column using an internal calibration reference substance. The analytical method was validated. The linearity of the detector response with respect to concentration was assessed for aqueous and organic phases respectively, and satisfactory correlation coefficient (r2) of 1.000 obtained. Mean log Pow values in the equilibration time for each replicate fell within a range of ± 0.3 log for the two main constituent isomers. equilibrium was evident from 214 hours equilibration time. Taking the results for samples 3, 4, 5 and 7 for each vessel, the slope of the correlation was tested statistically to ensure it did not differ significantly from zero. This was performed using the t test and a probability value of P = 0.05 (critical value = 4.30 for 2 degrees of freedom). A slope not significantly different from zero of at least 4 points verified the attainment of equilibrium. The octanol / water partition coefficient was determined to be log Pow = 4.23 to 4.29 at 25 ± 0.5 °C and pH 6.4..

Description of key information

log Pow (slow stir) = 4.23 to 4.29 at 25 ± 0.5 °C and pH 6.4, OECD TG 123, 2014

Key value for chemical safety assessment

Log Kow (Log Pow):
4.29
at the temperature of:
25 °C

Additional information

Key study : OECD TG 123, 2014 : The octanol / water partition coefficient was determined to be log Pow = 4.23 to 4.29 at 25 ± 0.5 °C and pH 6.4. The partition coefficient of the substance was determined according to OECD TG 123 slow stirring method under GLP, at 25 ± 0.5 °C from three independent replicates (test vessels) with four utilised out of seven sub-replicates (samples). Three sub-replicates were excluded due to problems with sample treatment and not utilised in further calculations. The pH-value of the aqueous phases was determined by a pH-meter. The pH of the aqueous phase at t=147 hours equilibration (before) was pH: 7.1 to 7.3 in all replicates and at t=478 hours equilibration (after) was pH: 6.4 – 6.5. Analytical evaluation was performed using GC-FID on a capillary analytical column using an internal calibration reference substance. The analytical method was validated. The linearity of the detector response with respect to concentration was assessed for aqueous and organic phases respectively, and satisfactory correlation coefficient (r2) of 1.000 obtained. Mean log Pow values in the equilibration time for each replicate fell within a range of ± 0.3 log for the two main constituent isomers. equilibrium was evident from 214 hours equilibration time. Taking the results for samples 3, 4, 5 and 7 for each vessel, the slope of the correlation was tested statistically to ensure it did not differ significantly from zero. This was performed using the t test and a probability value of P = 0.05 (critical value = 4.30 for 2 degrees of freedom). A slope not significantly different from zero of at least 4 points verified the attainment of equilibrium. The octanol / water partition coefficient was determined to be log Pow = 4.23 to 4.29 at 25 ± 0.5 °C and pH 6.4.

Applicant assessment indicates: the log Pow of each chromatographic constituent peak > 1% was determined within the study. The two main peaks (peak area > 10%) are reported as the substance log Pow range: 4.23 to 4.29 at 25 ± 0.5 °C and pH 6.4. All other peaks < 10% peak area had : log Pow 3.63 to 4.04. These are excluded from further consideration. The two main chromatographic peaks are considered to be the main constituent isomers and/or are most relevant for Classification and Labelling and Environmental Risk Assessment.