Registration Dossier

Administrative data

Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
27.-28. March 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
other: OECD guideline 105
Principles of method if other than guideline:
The determination of the log Pow using the respective OECD guideline methods was technically not feasible due to the intrinsic properties of the test item:
- The test item is a UVCB and the flask-shake (OECD TG 107) and slow-stir method (OECD TG 123) for determination the log Pow are not applicable to complex mixtures.
- The test item cannot be chromatographed under the conditions described in the HPLC-method (OECD Guideline 117) since it is insoluble in the solvents used for the reverse phase HPLC.
- The test item has no defined chemical structure; therefore the calculation of the log Pow with a QSAR tool is not possible.
Hence, the log Pow has to be estimated based on individual solubility of the test item in water and n-octanol
GLP compliance:
no
Type of method:
estimation method (solubility ratio)
Partition coefficient type:
octanol-water

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
Test Item: Leuco Sulfur Blue 15
Appearance: Dark, near black powder

Study design

Analytical method:
photometric method
other: observation of precipitated substance particles in n-octanol

Results and discussion

Partition coefficient
Key result
Type:
log Pow
Partition coefficient:
-0.9
Temp.:
20 °C
pH:
ca. 2.9
Remarks on result:
other: pH as determined in water solubility study
Details on results:
Undissolved particles were still observed in the test item / n-octanol mixture at the concentration 1 mg test item / 2 L n-octanol after 24 hours.
Based on this observation, the solubility of the test item in n-octanol is less than 0.5 mg/L.
The solubility of the test item in water is 4.1mg/L as determined in a separate GLP study (see "water solubility")
The Pow value of the test item is calculated by dividing the value for octanol solubility by the value for water solubility: Pow = <0.5 ml/L / 4.1 mg/L = <0.12.

Applicant's summary and conclusion

Conclusions:
The log Pow of the test item was determined to be -0.9.
Executive summary:

The determination of the log Pow using the respective OECD guideline methods was technically not feasible due to the intrinsic properties of the test item:

- The test item is a UVCB and the flask-shake (OECD TG 107) and slow-stir method (OECD TG 123) for determination the log Pow are not applicable to complex mixtures.

- The test item cannot be chromatographed under the conditions described in the HPLC-method (OECD Guideline 117) since it is insoluble in the solvents used for the reverse phase HPLC.

- The test item has no defined chemical structure; therefore the calculation of the log Pow with a QSAR tool is no possible.

Hence, the log Pow has to be estimated based on individual solubilities of the test item in water and n-octanol. Considering the water solubility of 4.1 mg/L and the n-octanol solubility of < 0.5 mg/L a log Pow of <0.9 has been estimated