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Physical & Chemical properties

Water solubility

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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:
OECD Guideline 105 (Water Solubility)
Deviations:
no
Qualifier:
according to
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 cS 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:

                                                                 cS 374 g/L

Description of key information

The water solubility cS 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:

                                                                 cS 374 g/L

Key value for chemical safety assessment

Additional information