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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:
2001-06-18 to 2002-03-08
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The partition coefficient was calculated based on the fact that a logPow of <-2 was obtained in the preliminary test
Reason / purpose:
reference to other study
Remarks:
Solubility in water was used to calculate the logPow value
Related information:
Composition 1
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
yes
Remarks:
The method could not be applied since the logPow is <-2 (preliminary test)
Qualifier:
according to
Guideline:
EU Method A.8 (Partition Coefficient)
Deviations:
yes
Remarks:
The method could not be applied since the logPow is <-2 (preliminary test)
Qualifier:
according to
Guideline:
other: Calculation method
Deviations:
no
Principles of method if other than guideline:
In the preliminary test, a very good solubility in water and a very poor solubility in n-octanol was found indicating a partition coefficient far below -2. Hence, a main test according to OECD Guidelines 107/117 (either HPLC or shake flask method) could not be applied. Therefore, the partition coefficient of the test substance was estimated using the solubility data in n-octanol (as obtained in the preliminary test) and in water. Concerning the solubility in water it is referred to in RCC study 821542 in section 4.8 Water solubility.
GLP compliance:
yes (incl. certificate)
Remarks:
Certificate from the Swiss GLP Monitoring Authorities
Type of method:
other: ratio of the solubility of tyhe test substance in the pure solvents
Partition coefficient type:
octanol-water
Test material information:
Composition 1
Specific details on test material used for the study:
- Batch n°: RT002102G4A311
- Analytical purity: 99.4%
- Expiration date: 25 March 2002
- Storage condition: at room temperature
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
-2.9
Temp.:
20 °C
pH:
ca. 7
Remarks on result:
other: The pH value was not mentioned, but the conditions are assumed neutral
Details on results:
- In the present study, the n-octanol solubility of the test substance was determined to be 51.8 ug/mL (see Table 1 below).
- The water solubility of the test substance was stated to be 36.4 g/L in the RCC study 821542. The latter result was used for the calculation of the partition coefficient.
- Using these values, the partition coefficient was determined to be -2.9

Table 1. Results obtained for the solubility of the test substance in n-octanol.

Initial weight of test item (mg) n-octanol added (mg)  Dilution factor  Area counts  Measured concentration (mg/L)  Solubility in n-octanol (µg/L)  Mean (mg/L) 
32  25 10 92954 5.01 50.1 -
38 25 10 99204 5.35 53.5 51.8
Conclusions:
In the preliminary test, a very good solubility in water and a very poor solubility in n-octanol was found indicating a partition coefficient far below -2. Hence, a main test according to OECD Guidelines 107/117 (either HPLC or flask shaking method) could not be applied. Therefore, the partition coefficient of the test substance was estimated using the solubility data in n-octanol (as obtained in the preliminary test) and in water. The resulting estimated log Kow was -2.9.

Description of key information

The log Pow of the substance was estimated to be -2.9 (RCC, 2002). In the preliminary test, a very good solubility in water and a very poor solubility in n-octanol was found indicating a partition coefficient far below -2. Hence, a main test according to OECD Guidelines 107/117 (either HPLC or flask shaking method) could not be applied. Therefore, the partition coefficient of the test substance was estimated using the solubility data in n-octanol (as obtained in the preliminary test) and in water. No data on temperature are reported, however the ambient temperature of 20°C is anticipated.

Key value for chemical safety assessment

Log Kow (Log Pow):
-2.9
at the temperature of:
20 °C

Additional information

In the preliminary test, a very good solubility in water and a very poor solubility in n-octanol was found indicating a partition coefficient far below -2. Hence, a main test according to OECD Guidelines 107/117 (either HPLC or flask shaking method) could not be applied . Therefore, the partition coefficient of the test substance was estimated using the solubility data in n-octanol (as obtained in the preliminary test) and in water and a Klimisch score 2 was assigned. The resulting estimated log Kow was -2.9.