Benzenesulfonic acid, 2,2'-(1,2-ethenediyl)bis[5-nitro-, reaction products with 4-[(4-aminophenyl)azo]benzenesulfonic acid, reduced, oxidized, potassium sodium salts

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

December 15, 2017 - April 10, 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

no

GLP compliance:

no

Type of method:

flask method

Key result

Water solubility:

> 374 g/L

Conc. based on:

test mat.

Loading of aqueous phase:

560 g/L

Temp.:

20 °C

pH:

> 7.9 - < 8.1

Preliminary test

In a stepwise procedure, increasing volumes of demineralized water were added at room temperature to a defined amount of the test item. After each addition of an amount of water the mixture was treated with ultrasound for 10 minutes and visually checked for any undissolved particles.

Table4: Results of the preliminary test

Amount of test item / mg	Added volume of demineralized water / mL	Total volume of demineralized water / mL	Appearance of mixture
104.3	0.1	0.1	not dissolved
	0.4	0.5	not dissolved
	0.5	1.0	dissolved

The preliminary test showed that the water solubility of the test item is > 10 mg/L. According to the preliminary test the water solubility was determined by the flask method in the main test. As the water solubility determined in the preliminary test was very high, an additional stirring test was performed to determine the highest amount of test item that can still be stirred sufficiently in a mixture with water.

Table5: Results of the stirring test

Amount of test item [g]	Added volume of demin. water [mL]	Total volume [mL]	Observation
10.67	10	10	could not be stirred
	5	15	could not be stirred
	1	16	could not be stirred
	1	17	could not be stirred
	1	18	could be stirred

According to the stirring test mixtures with a concentration of approx. 560 g/l test item in demin. water were used in the main test.

 Flask method

The flask method was performed as described above. The data for the evaluation are given in Table6. After the equilibration time precipitate was observed in the flasks of the experiments excluding in the blank experiment.The water solubility was calculated from the measured and unrounded concentration values and not from the rounded values given in Table6.

Table6: Water solubility experiments of the test item

Experiment	24 h experiment	48 h experiment	72 h experiment	168 h experiment	Blank experiment (72 h)
Amount of test item / g	10.19	10.45	10.36	10.32	--
Amount of demineralized water / mL	18	18	18	18	18
Stirring time at 30 °C / h	24	48	72	168	72
pH at 24 °C	7.9	7.9	7.9	8.1	6.9
Dilution factor	168801	163274	161339	156130	156250
Measured concentration / mg/L	2.22 / 2.21	1.58 / 1.58	1.12 / 1.12	0.54 / 0.54	-- / --
Mean concentration / mg/L	2.22	1.58	1.12	0.54	--
Water solubility / g/L	374	258	181	84	--

The measured concentration of the test item decreased with increasing stirring time. As a conservative approach, the water solubility of the test item at 20 °C was determined to be ≥374 g/L

Executive summary:

The water solubility c_S of the test item Direct Orange 57 at a temperature of 20 °C was determined according to the flask method. Without correction of the purity it was found to be:

                                                                 c_S ≥ 374 g/L

Description of key information

The water solubility c_S of the test item Direct Orange 57 at a temperature of 20 °C was determined according to the flask method. Without correction of the purity it was found to be:

                                                                 c_S ≥ 374 g/L