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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:
2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 1
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient)
Deviations:
no
GLP compliance:
yes
Type of method:
shake-flask method to: flask method
Partition coefficient type:
octanol-water
Test material information:
Composition 1
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
ca. 1.298
Temp.:
22 °C
pH:
>= 4.81 - <= 4.91
Details on results:

Sample molecular weight 412.47 grams per mole. Stock solution was prepared with 199.31mg of sample in 300 mL octanol.

A slight cloudiness was observed at the interface between the octanol and water layer. A late running peak (retention time 5.7 minutes) was observed in the HPLC analysis.

See attached document 'Software Estimation'

See attached document ' Analytical Determinations'

Conclusions:
Mean partition coefficient result (Log Pow): 1.298
Executive summary:

The partition coefficient (also known as distribution coefficient) is a physicochemical property of a material, which reflects the relative aqueous, and lipid solubilities and ionization behaviour. The phase distribution is independent of the concentration of dilute species.

The shake flask method is generally applicable for the determination of the Partition Coefficient (Log Pow) of a given material where the Log Pow value is expected to fall within the range –2 to +4. It is also applicable for essentially pure substances that are soluble in

water and n-octanol but not applicable to surface-active materials.

The test is generally dependent on the Nernst Partition Law, which applies only at constantemperature, pressure and pH for dilute solutions of pure substances. Dissociation or association of dissolved molecules may affect the Log Pow of a material because such

behaviour results in deviations from the Nernst Partition Law. Therefore it is imperative to have preliminary information on structural formula, dissociation constant, water solubility, hydrolysis and surface tension of the test material prior to the analysis.

The test is conducted in accordance with the procedure described in EU Regulation (EC) 440/2008, Annex Part A test A8.

The partition coefficient was appraised using computer software which uses the chemical structure to provide an estimated value. The estimate of the KOWWIN v1.68 software was 1.38.

The formal partition coefficient analysis was carried out afterwards, according to test guideline A.8 of EU Regulation 440/2008. The experimental result for octanol/water partition coefficient was LogKow = 1.298.

Description of key information

The partition coefficient analysis was carried out according to test guideline A.8 of EU Regulation 440/2008. The experimental result for octanol/water partition coefficient was LogKow = 1.298.

Key value for chemical safety assessment

Log Kow (Log Pow):
1.298
at the temperature of:
22 °C

Additional information