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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:
2006
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Qualifier:
according to guideline
Guideline:
EU Method A.8 (Partition Coefficient - HPLC Method)
GLP compliance:
yes (incl. QA statement)
Type of method:
HPLC method
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
> 5.84
Remarks on result:
other: pH and Temp. not indicated
Details on results:
Taking into account the molecular weight of 350.5, the 0.01 M concentration suggested by the Official Journal L 383 A.8 method should be 3.505 g/L (3505 mg/L).
At this concentration a clear solution was obtained in n-octanol while the water solubility was determined to be < 0.5 µg/ (see the determination reported above).

Therefore:
Partition Coefficient (Pow) = 3505 mg/L / 0.005 mg/L = 701000 and therefore log Pow = 5.84

Since in presence of both water and n-octanol solvents, considering the very high difference between the two solubilities, the test article is dissolved principally in the organic phase, the concentration in the aqueous phase should be lower than the saturation value.
Therefore, it can be estimated that the partition coefficient between n-octanol and water should be higher than the ratio between the two solubilities.
(Pow) > 701000 log Pow > 5.84
Conclusions:
(Pow) > 701000 and log Pow > 5.84
Considering that variations of temperature does not significantly changes the solubility of the test article in n-octanol, it is reasonable to conclude that also the partition coefficient values is constant with respect to temperature or pH variations.
Executive summary:

The partition coefficient of the test material has been tested according to the following guidelines methods: OECD 107 and EU A. 8.

The partition coefficient was estimated to be: (Pow) > 701000 or reported as log Pow > 5.84

For changes in the temperature or pH value and considering that variations of temperature does not significantly changes the solubility of the test article in n-octanol, it is reasonable to conclude that also the partition coefficient values is constant with respect to environmentally relevant temperature or pH variations.

Description of key information

The partition coefficient of the test material has been tested according to the following guidelines methods: OECD 107 and EU A. 8.

Since the test material presented a very low solubility in water and a high solubility in n-octanol, no instrumental analysis was performed and a limit value for the partition coefficient between n-octanol and water was calculated on the basis of the solubilities in two phases.

It can be estimated that the partition coefficient between n-octanol and water should be higher than the ratio between the two solubilities and therefore, Pow is > 701000 or reported as log Pow > 5.84.

Key value for chemical safety assessment

Log Kow (Log Pow):
5.84
at the temperature of:
20 °C

Additional information