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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:
April 27, 2018 - May 04, 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:
< 0.21 mg/L
Conc. based on:
test mat.
Loading of aqueous phase:
989 mg/L
Temp.:
20 °C
pH:
> 6.4 - < 7.2

Preliminary  test

Three preliminary tests were carried out with specified amounts of the test item and 100 mL, 500 mL and 1000 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

12.4

100

not dissolved

14.6

500

not dissolved

8.9

1000

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

98.9 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. 20 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 24 °C: 7.0). 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 THF. 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. Refer to Table 5 to Table 7 for results.

Column 1:

Rotation period of the fraction collector:                 90 min per fraction

Duration of sampling:                                             about 50 h (33 fractions)

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

Fraction no.

V / mL

pH

water solubility /µg/L

20

16.0

6.4

<208

21

15.5

7.0

<208

22

15.5

7.1

<208

23

15.5

7.2

<208

24

15.0

7.0

<208

The water solubility was found to be below the quantification limit of 208 µg/L.

 

 

 

Column 2:

Rotation period of the fraction collector:       45 min per fraction

Duration of sampling:                                    about 46 h (61 fractions)

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

Fraction no.

V / mL

pH

water solubility /µg/L

40

12.5

6.8

<208

41

12.5

6.9

<208

42

13.0

7.0

<208

43

13.0

7.0

<208

44

13.5

7.0

<208

The water solubility was found to be below the quantification limit of 208 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

24.7

3.588 / 3.621

18.02

Column 25.0 mL/h

3.977 / 4.018

19.99

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

The water solubility cS of the test item Disperse Red 91 was below the quantification limit of 208 µg/L (mean value of the columns).

Executive summary:

The water solubility cS of the test item Disperse Red 91 at a temperature of 20 °C was determined according to the column elution method. It was found to be below the quantification limit:

cS < 0.21 mg/L

Description of key information

The water solubility cS of the test item Disperse Red 91 at a temperature of 20 °C was determined according to the column elution method. It was found to be below the quantification limit:

cS < 0.21 mg/L

Key value for chemical safety assessment

Additional information