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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:
27.11.96 to 07.02.97
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)
Qualifier:
equivalent or similar to
Guideline:
EU Method A.8 (Partition Coefficient)
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 were found indicating a partition coefficient below -2. Hence, a main test according to OECD Guidelines 107/117 (either HPLC or flask shaking method) could not be applied.
GLP compliance:
yes (incl. certificate)
Remarks:
Switzerland GLP
Type of method:
other: estimated from its solubility in n-octanol and in water
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: WP2/96
- Expiration date of the lot/batch: November 30, 2004

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: At room temperature at about 20 °C
- Stability under test conditions: ~ 50 g/l (20 °C)
- Solubility of the test substance in the solvent/vehicle: At least 48 h in water
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
-5.4
Remarks on result:
other: calculated using the solubility in n-octanol and water respectively.

In the present study, the n-octanol solubility of FAT 45'176/A was determined to be < 1.131 pg/l, which is below the smallest calibration point. No peak was detected at the relevant retention time.

The water solubility of the test article was estimated to be about 570 g/l* in the pretest and was stated to be 330 g/l in the Test Report No. FC-96/1 OT.WS, CIBA-GEIGY Ltd., CH- 4002 Basel. The latter result was used for the calculation of the partition coefficient.

Thus, the partition coefficient, log Pow, of FAT 45'176/A was calculated to be

log Pow = log    1.313mg/l            = -5.4

                       330 • 1000 mg/l

Conclusions:
The partition coefficient, log PoW of FAT45'176/A was calculated from the individual solubilities in n-octanol and in water was -5.4.
Executive summary:

Neither the HPLC-method (OECD 117 Guideline) nor the flask-shaking method (OECD 107 Guideline) were applicable for the determination of the partition coefficient of FAT45'176/A. Thus, the log Pow-value for FAT 45176/A was estimated from its solubility in n-octanol and in water, respectively.

In conclusion, the partition coefficient, log Pow of FAT45'176/A was calculated from the individual solubilities in n-octanol and in water, respectively, to be -5.4.

Description of key information

log Pow of Reactive Orange 136 was -5.4.

Key value for chemical safety assessment

Log Kow (Log Pow):
-5.4

Additional information

Neither the HPLC-method (OECD 117 Guideline) nor the flask-shaking method (OECD 107 Guideline) were applicable for the determination of the partition coefficient of FAT45'176/A. Thus, the log Pow-value for FAT 45176/A was estimated from its solubility in n-octanol and in water, respectively.

In conclusion, the partition coefficient, log Pow of FAT45'176/A was calculated from the individual solubilities in n-octanol and in water, respectively, to be -5.4.