Reaction mass ofDisodium [1-{[2-(hydroxy-kO)-3,5-dinitrophenyl]diazenyl-kN1}naphthalen-2-olato(2-)-kO][3-(hydroxy-kO)-4-{[2-(hydroxy-kO)naphthalen-1-yl]diazenyl-kN1}-7-nitronaphthalene-1-sulfonato(3-)]chromate(2-) andDisodium [1-{[2-(hydroxy-kO)-3,5-dinitrophenyl]diazenyl-kN2}naphthalen-2-olato(2-)-kO][3-(hydroxy-kO)-4-{[2-(hydroxy-kO)naphthalen-1-yl]diazenyl-kN1}-7-nitronaphthalene-1-sulfonato(3-)]chromate(2-)

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Experimental starting date - 15 October 2015; Experimental completion date - 16 October 2015; Study completion date: 21 October 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.8 (Partition Coefficient)

Deviations:

no

GLP compliance:

no

Type of method:

flask method

Partition coefficient type:

octanol-water

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: FAT 20037/E TE Lot.: 1501016

Analytical method:

photometric method

Type:

Pow

Partition coefficient:

2.28

Temp.:

20 °C

Remarks on result:

other: pH not available

Key result

Type:

log Pow

Partition coefficient:

0.357

Temp.:

20 °C

Remarks on result:

other: pH not available

Preliminary visual estimation of the n-octanol solubility

Different amounts of the test item were stirred with different amounts of n-octanol at room temperature and visually checked for any undissolved particles.

Amount of the test item in mg	Volume in mL	Total volume in mL	Stirring time	Appearance of mixture
10	1	1	60 min	undissolved
10	2.5	2.5	60 min	undissolved
10	5.0	5	60 min	dissolved
10	10	10	60 min	dissolved

According to this preliminary test the solubility of the test item in n-octanol is about 2 g/L (without correction of the purity).

The partition coefficient Pow may be estimated from the saturation concentrations in n-octanol and water by the following equation:

P ow = cs octanol /cs water

where s= saturation

With the data obtained from the experiments (cs = 2 g/L) and in the preliminary test (water solubility: cs = 55 g/l) the partition coefficient was calculated as log P_OW -1.4.

Determination of the solubility in the n-Octanol phase: Flask Method

Experiment	A	B	C	D (blank)
Amount of test item [mg]	1000	1000	1000	-
Stirring time at 30 °C [h]	24	48	72	72
Aliquot of the flasks (mL)	0.25	0.25	0.25	0.5
End volume (mL)	10	10	10	10
Measured concentration [μg/mL]	47.2	46.4	47.9	-
Solubility [g/L]	1.9	1.9	1.9	-

The values of the measured concentrations of the test item in n-octanol is 3.7 g/L. In order to evaluate accuracy, a recovery check was carried out, in which the recovery was 101.3% indicating a sufficient accuracy of the analytical method.

Shake Flask method

A stock solution of the test item was prepared in water (pre-saturated with octanol): 30.2 mg/100 mL. Three different experiments (double determination) was started with following ratios of octanol/water: A (1:1); B (1:2); C (2:1). After phase separation by centrifugation, the total concentration of the test substance was determined by VIS-spectroscopy (577 nm) at 20°C in each phase.

Determination of the partition coefficient

Experiment Ratio octanol/water	A Ratio 1:1	B Ratio 1:2	C Ratio 2:1
Stock solution in mg/100 mL	30.2	30.2	30.2
Stock solution in mL	4	8	4
Flask concentration in μg	1210	2420	1210
Water volume in mL	4	8	4
Aliquot (water phase)	1/10	1/10	1/10
Aliquot (octanol phase)	1/10	1/10	1/10
Measured concentration n-octanol phase (μg/mL)	24.3	38.2	12.4
Measured concentration water phase (μg/mL)	10.6	11.3	8.8
Measured concentration n-octanol phase (μg)	974	1526	995
Measured concentration water phase (μg)	422	904	352
POW	2.31	1.69	2.83
Log POW	0.363	0.227	0.451

Conclusions:

The n-octanol/water partition coefficient of the test item was determined to be 2.28 (log Pow = 0.357).

Executive summary:

The partition coefficent of the test item was determined in a study conducted according to OECD Guideline 107 and EU Method A.8. Shake flask method was used for this purpose.

Based on the findings of the study, the n-octanol/water partition coefficient of the test item was determined to be 2.28 (log Pow = 0.357).

Description of key information

The partition coefficent of the test item was determined in a study conducted according to OECD Guideline 107 and EU Method A.8. Shake flask method was used for this purpose. Based on the findings of the study, the n-octanol/water partition coefficient of the test item was determined to be 2.28 (log Pow = 0.357).

Key value for chemical safety assessment

Log Kow (Log Pow):

0.357

at the temperature of:

20 °C