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Water solubility

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Reference
Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
March 29, 2018 - April 06, 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:
column elution method
Key result
Water solubility:
< 63 µg/L
Conc. based on:
test mat.
Loading of aqueous phase:
993 mg/L
Temp.:
20 °C
pH:
> 6.6 - < 6.8

Preliminary  test

Three preliminary tests were carried out with specified amounts of the test item and 100 mL and 500 mL demineralized water, respectively. After each addition of an amount of water, the mixture was stirred for at least 24 hours, and visually checked for any undissolved particles.

Table4: Results of the preliminary test

Amount

of test item / mg

Total volume of demineralized water / mL

Appearance of mixture

8.0

100

not dissolved

12.1

500

not dissolved

4.6

500

not 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 column elution method in the main test.

Column elution  method

99.3 mg of the test item were dissolved in 100 mL tetrahydrofuran. For charging the columns in each case 25 mL of the test item solution was added to about 3 g of sea sand and the mixtures were shaken. The solvent was then removed under reduced pressure using a rotary evaporator (40 °C, approx. 10 mbar). The dry residues were placed into the columns of the test apparatus, which have afterwards been filled with water (test temperature: 20 °C; water pH at 23 °C: 6.7). After a swelling time of 2 h pumps were started to rinse the test item coated sand with demineralized water. At the end of the study it was confirmed that residual test item remained on the columns. The residual test item was eluted with 50 mL acetone. As blank value the used demineralized water was tested. No signal was detected in the range of the retention time of the test item. The concentration of the test item was quantified by HPLC.

Column 1:

Rotation period of the fraction collector:                 90 min per fraction

Duration of sampling:                                             about 74 h (49 fractions)

Table5: Column elution method, column 1 (approximately 12.5 mL/h)

Fraction no.

V / mL

pH

water solubility /µg/L

20

10.0

6.8

< 63.2

21

10.0

6.7

< 63.2

22

9.7

6.6

< 63.2

23

9.7

6.6

< 63.2

24

9.3

6.6

< 63.2

The water solubility was found to be below the quantification limit of 63.2 µg/L.


 

Column 2:

Rotation period of the fraction collector:       45 min per fraction

Duration of sampling:                                    about74 h(98 fractions)

Table6: Column elution method, column 2 (approximately 25.0 mL/h)

Fraction no.

V / mL[1]

pH

water solubility /µg/L

40

9.3

5.9

< 63.2

41

9.3

6.5

< 63.2

42

9.3

6.5

< 63.2

43

9.3

6.5

< 63.2

44

9.3

6.6

< 63.2

The water solubility was found to be below the quantification limit of 63.2 µg/L.

In both columns the concentration of five consecutive fractions was constant within ± 30 %. No increasing or decreasing tendency was observed.

Coating check:

Table7: Coating check

 

Amount of test item used for coating / mg

Measured concentration of test item in eluate / mg/L

Amount of test item eluted

/ mg

Column 12.5 mL/h

27.1

1.665 / 1.664

8.32

Column 25.0 mL/h

2.056 / 2.053

10.27

The coating check was successful. Enough test item remained on the columns.

Witout correction of the purity, the water solubility cS of the test item Disperse Yellow 71 was below the quantification limit of 63.2 µg/L (mean value of the columns).


[1]Small particles of the test item blocked the column so that the volume flow was smaller than usually. This had no effect on the final results.

Executive summary:

The water solubility cS of the test item Disperse Yellow 71 at a temperature of 20 °C was determined according to the column elution method. It was found to be below the quantification limit:

cS < 0.063 mg/L

Description of key information

The water solubility cS of the test item Disperse Yellow 71 at a temperature of 20 °C was determined according to the column elution method. It was found to be below the quantification limit:

cS < 0.063 mg/L

Key value for chemical safety assessment

Additional information