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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:
2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
equivalent or similar to guideline
Guideline:
other: OECD Guideline 105 and ETAD method
Principles of method if other than guideline:
To measure the partition coefficient of pigments utilising the standard OECD Guideline 107 is extremely difficult because of the problems associated with the inherent very low solubilities. The following procedure is used for determining the LogPow of low solubility substances and in particular that of pigments.
The partition coefficient was estimated based on the ratio of the solubilities in n-octanol and in water. The individual solubilities were determined by flask method based on OECD Guideline 105 and the ETAD method.
GLP compliance:
no
Type of method:
estimation method (solubility ratio)
Partition coefficient type:
octanol-water
Specific details on test material used for the study:
- Name of test material (as cited in study report): Pigment Rot 52:Sr
- Physical state: powder
- Lot/batch No.: JW111201
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
1.22
Temp.:
23 °C
Remarks on result:
other: pH was not reported

The concentration of the pigment in water and in n-octanol was determined by HPLC-UV

Average concentration of 3 tests:

Cn-octanol= 197µg/L

Cwater= <15µg/L

The n-octanol/water partition coefficient can be approximated with the following equation:

Pow= (Cn-octanol/ Cwater)= 16.7

logPow= 1.22

Description of key information

Estimated based on solubility ratio:

log Pow = 1.22 at 23°C

Key value for chemical safety assessment

Log Kow (Log Pow):
1.22
at the temperature of:
23 °C

Additional information

The partition coefficient was estimated based on the ratio of the solubilities in n-octanol and in water.

The individual solubilities were determined by flask method based on OECD Guideline 105 and the ETAD method. The quantification was analyzed by UV/Vis absorption.

The non-resin-coated test substance is representative pure substance therefore its data has been chosen as the key study.