1,4-bis[(2,6-diethyl-4-methylphenyl)amino]anthraquinone

Partition coefficient

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

partition coefficient

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

An analogue is chosen as a read-across for this endpoint due to the structural similarity.

Reason / purpose for cross-reference:

read-across source

Key result

Type:

log Pow

Partition coefficient:

8.6

Temp.:

25 °C

pH:

5.3

Reference 2

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 06 June 2016 to 01 February 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 117 (Partition Coefficient (n-octanol / water), HPLC Method)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

HPLC method

Partition coefficient type:

octanol-water

Analytical method:

high-performance liquid chromatography

Type:

log Pow

Partition coefficient:

8.6

Temp.:

40 °C

pH:

5.3

Details on results:

The reference Pow-values in the OECD-guideline presumably refer to 25 °C. Even though the column temperature was 40 °C, this temperature is without influence on the result of the determination. The calibration was done referring to Pow- values of reference substances determined at 25 °C.
The chromatogram of the test item showed 1 signal eluting at 20.3 minutes. No calibration substance with a Pow–value above the value for the signal of the test item was available. For this reason the results for this signal was extrapolated.

The pKa values, calculated with the software ACD/Labs/Percepta 14.0.0 Release 2012 at the structure of the test item, were:

pKa(Acid): No acid pKa

First pKa(Base): - 4.5 +/- 0.2

Second pKa(Base): -0.9 +/- 0.2

Therefore the undissociated form (nonionic from) of the test item exists at a pH value > -0.9 and the test can be carried out in buffered water at pH 5.

Conclusions:

The partition coefficient (logPow) of the test item was determined to be 8.6 at 25 °C (pH 5.3).

Executive summary:

The partition coefficient of the test item was determined by the HPLC-method according to OECD TG 117, and under GLP.

The system was calibrated with six reference substances. The partition coefficient was determined to be 8.6 at 40°C, and is considered to also refer to 25 °C. All validity criteria were met.

Description of key information

The partition coefficient (logPow) of the test item (analogue) was determined to be 8.6 at 25 °C (pH 5.3). (OECD 117, 2017)

Key value for chemical safety assessment

Log Kow (Log Pow):

8.6

at the temperature of:

25 °C

Additional information

This endpoint was covered by read-across of a study of 1,4-bis[(2-ethyl-6-methylphenyl)amino]anthraquinone. This read-across is justified as both substances have very similar chemical structures, the main physicochemical parameters (vapour pressure, water solubility and dissociation constant) are in the same range and further all available toxicological studies for both substances revealed the same results. Therefore a read-across for other physicochemical, ecotoxicological or toxicological endpoints seems to be justified. More details about the read-across justification are displayed in a detailed document attached to the Annex of the CSR.