2-Naphthalenesulfonic acid, 5(or 8)-amino-, reaction products with 4-aminophenol and sodium sulfide (Na2(Sx))

Partition coefficient

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

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

Test material information

Constituent 1

Reference substance name:

2-Naphthalenesulfonic acid, 5(or 8)-amino-, reaction products with 4-aminophenol and sodium sulfide (Na2(Sx))

EC Number:

309-304-0

EC Name:

2-Naphthalenesulfonic acid, 5(or 8)-amino-, reaction products with 4-aminophenol and sodium sulfide (Na2(Sx))

Cas Number:

100208-97-7

Molecular formula:

not applicable

IUPAC Name:

2-Naphthalenesulfonic acid, 5(or 8)-amino-, reaction products with 4-aminophenol and sodium sulfide (Na2(Sx))

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