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Partition coefficient

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Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
other: OECD Guideline 105 (Water Solubility)
Deviations:
yes
Remarks:
see 'Principles of method if other than guideline'
Principles of method if other than guideline:
The 1-octanol solubility of test substance was determined according to water solubility. Afterwards a quotient of both solubilities was formed to obtain the partition coefficient.
GLP compliance:
yes (incl. certificate)
Type of method:
flask method
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Type:
log Pow
Partition coefficient:
-2.49
Temp.:
20 °C
Remarks on result:
other: No pH-value reported
Details on results:
Due to the fact that the values for water solubility as well as for the 1-octanol solubility are no exact values, the estimation of the logPOW is defective. Nevertheless it can be stated that the octanol solubility is definitely much lower than the water solubility. Therefore it can be adopted that in each case the logPow is lower than 0.

The test item consists of solid crystals. The crystals are not all of the same size. Therefore the size of the crystals which were used for the saturation of 1-octanol could be a possible factor of influence on the duration until saturation. It is assumed that the saturation is not completely reached in all flasks, based on the result of 952 mg/L. It is assumed that for this flask a portion of smaller crystals was used.

Conclusions:
For Special Brilliant Blue FFR a logPow of -2.49 is calculated as an approximated value.
Executive summary:

The partition coefficient of Special Brilliant Blue FFR was calculated as quotient of its 1-octanol and its water solubility.

Both solubilities were determined according to OECD 105 with deviations due to the test items characteristics. The determination of water solublity is described in another chaper (water solubility).

To determine the 1 -octanol solubility a quantity of Special Brilliant Blue FFR nessary for saturation was weighed into Erlenmeyer flasks. 100 mL 1-Octanol was added. The flasks were tightly stoppered and then stirred with a magnetic stirrer in a temperature-controlled water bath (Flask A: 192 hours at 30 °C and 24 hours at 20 °C, Flask B: 144 hours at 30 °C and 24 hours at 20 °C, Flask C: 96 hours at 30 °C and 24 hours at 20 °C, Flask D: 168 hours at 30 °C and 24 hours at 20 °C, Flask E: 192 hours at 30 °C and 24 hours at 20 °C.

A 1-octanol solubility of at least 952 mg/L was determined. As water solubility was determined as >= 292 g/L, a partition coefficient of -2.49 was calculated as approximated value.

Due to the fact that the values for water solubility as well as for the 1-octanol solubility are no exact values, the estimation of the logPOW is defective. Nevertheless it can be stated that the octanol solubility is definitely much lower than the water solubility. Therefore it can be adopted that in each case the logPow is lower than 0.

The test item consists of solid crystals. The crystals are not all of the same size. Therefore the size of the crystals which were used for the saturation of 1-octanol could be a possible factor of influence on the duration until saturation. It is assumed that the saturation is not completely reached in all flasks, based on the result of 952 mg/L. It is assumed that for this flask a portion of smaller crystals was used.

Description of key information

The partition coefficient of Special Brilliant Blue FFR was calculated as quotient of its 1-octanol and its water solubility.

Both solubilities were determined according to OECD 105 with deviations due to the test items characteristics.

A 1-octanol solubility of at least 952 mg/L was determined. As water solubility was determined as >= 292 g/L, a partition coefficient of -2.49 was calculated as approximated value.

Due to the fact that the values for water solubility as well as for the 1-octanol solubility are no exact values, the estimation of the logPOW is defective. Nevertheless it can be stated that the octanol solubility is definitely much lower than the water solubility. Therefore it can be adopted that in each case the logPow is lower than 0.

The test item consists of solid crystals. The crystals are not all of the same size. Therefore the size of the crystals which were used for the saturation of 1-octanol could be a possible factor of influence on the duration until saturation. It is assumed that the saturation is not completely reached in all flasks, based on the result of 952 mg/L. It is assumed that for this flask a portion of smaller crystals was used.

Key value for chemical safety assessment

Log Kow (Log Pow):
-2.49
at the temperature of:
20 °C

Additional information