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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:
2013-10-24 - 2013-10-31
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
It should be noted that the pKa of the substance indicates that the test should have been performed at a pH one pH unit above the pKa (free base). However, a partition coefficient at a more relevant pH is considered more applicable and hence the resulting value (actually the log D value at pH 8.0-8.3) can be accepted.
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient)
Deviations:
yes
Remarks:
The substance is inoizable and hence the test should have been performed on the substance in its non-ionized form
GLP compliance:
yes
Type of method:
shake-flask method to: flask method
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
- Name of test material (as cited in study report): Dimethyl Piperazine
- Substance type: Clear liquid
- Physical state: Liquid
- Lot/batch No.: 1903-3/2012
Analytical method:
other: UV-spectrophotometric analysis
Key result
Type:
log Pow
Partition coefficient:
-0.26
Temp.:
20 °C
pH:
8 - 8.3
Details on results:
Preliminary estimation: the sample appeared completely miscible in both water and 1-octanol. As a result a Log Pow could not be estimated from the preliminary test.

As the preliminary test revealed no estimated Log Pow, this value has been determined from software predictions to be -0.4.

Formal analysis:

Due to the apparent complete miscibility observed in both phases it is possible that properties such as density and functionality will have a disproportionate effect on the LogP value obtained practically. Due to this, consideration should be given to the LogP values obtained from software estimation.

Software estimation:

The prediction software uses SMILES input to calculate the partition coefficient.

Log Octanol-Water Partition Coef (SRC)

Log Kow (Experimental Database match) = -0.40

Exper. Ref: Hansch, C et al. (1995)

Conclusions:
The octanol/water partition coefficient (log Pow) of the test substance was determined as -0.26 at pH 8.0 - 8.3 and 20°C.

Description of key information

The log Pow of the test substance was determined to be -0.26 in a GLP study with EU method A.8 at 20°C and pH 8.0-8.3, following the shake-flask method (Younis, 2013).

Key value for chemical safety assessment

Log Kow (Log Pow):
-0.26
at the temperature of:
20 °C

Additional information