Disodium [3-[(4,5-dihydro-3-methyl-5-oxo-1-phenyl-1H-pyrazol-4-yl)azo]-4-hydroxy-5-nitrobenzenesulphonato(3-)][2-[(2-hydroxybenzylidene)amino]-4-nitrophenolato(2-)-N2,O1,O2]chromate(2-)

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

April 13, 2018 - May 02, 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:

507 g/L

Conc. based on:

test mat.

Loading of aqueous phase:

764 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 15 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
108.6	0.1	0.1	not dissolved
	0.4	0.5	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.

Flask method

The flask method was performed as described above. The data for the evaluation are given in Table5. After the equilibration time precipitate was observed in the flasks of the experiments excluding in the blank experiment.Asthe resulting solutions of the experiments were too concentrated for pipetting aliquots were weighted in graduated flasks and filled up to 10 mL with demin. water. Therefore the measured density of 1.14 was used to calculate the volume of the aliquots of the flasks. The water solubility was calculated from the measured and unrounded concentration values and not from the rounded values given in Table5.

Table5: 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	15.277	15.007	15.087	15.298	--
Amount of demineralized water / mL	20	20	20	20	20
Stirring time at 30 °C / h	24	48	72	168	72
pH at 24 °C	8.1	8.0	7.9	8.0	6.2
Aliquots of the flasks / mg	61.8	80.5	75.8	61.3	750
Aliquots of the flasks / mL	0.054	0.071	0.066	0.054	0.750
1^stDilution / mL	10	10	10	10	10
Aliquot of the flasks / mL	0.05	0.05	0.05	0.05	0.05
2^ndDilution / mL	1.0	1.0	1.0	1.0	1.0
Dilution factor	3700	2817	3030	3704	267
Measured concentration / mg/L	137.48 / 136.99	162.36 / 162.24	96.69 / 96.58	73.30 / 72.94	-- / --
Mean concentration / mg/L	137.2	162.3	96.6	73.1	--
Water solubility / g/L	507	460	291	272	--

The water solubilities showed a decreasing tendency. As a conservative approach the highest value was stated. The water solubility of the test item at 20 °C was determined to be 507 g/L.

Executive summary:

The water solubility c_S of the test item Acid Orange 166 at a temperature of 20 °C was determined according to the flask method. It was found to be without correction of the purity:

                                                                 c_S = 507 g/L

Description of key information

The water solubility c_S of the test item Acid Orange 166 at a temperature of 20 °C was determined according to the flask method. It was found to be without correction of the purity:

                                                                 c_S = 507 g/L

Key value for chemical safety assessment

Water solubility:

507 g/L

at the temperature of:

20 °C