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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:
July 20, 2017 - September 01, 2017
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:
> 0.16 - < 0.32 mg/L
Conc. based on:
test mat.
Loading of aqueous phase:
1 060 mg/L
Temp.:
20 °C
pH:
6.7

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

13.4

100

not dissolved

12.4

500

not dissolved

4.1

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

106.0 mg of the test item were dissolved in 100 mL dichloromethane. 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 (35 °C, approx. 30 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: 6.5). 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 dichloromethane. 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 99 h (66 fractions)

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

Fraction no.

V / mL1

pH

water solubility

/µg/L

45

6.0

6.7

0.338

46

7.0

6.7

0.310

47

6.2

6.7

0.312

48

6.2

6.7

0.315

49

6.0

6.7

0.284

The water solubility was found to be 312 µg/L.


 

Column 2:

Rotation period of the fraction collector:       45 min per fraction

Duration of sampling:                                    about96 h(127 fractions)

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

Fraction no.

V / mL[1]

pH

water solubility

/µg/L

90

1.6

6.6

0.157

91

1.6

6.6

0.163

92

1.6

6.7

0.185

93

1.6

6.7

0.165

94

1.6

6.7

0.173

The water solubility was found to be 169 µg/L.

In both columns the concentration of five consecutive fractions was constant within ± 30 %. The results of the two columns showed a deviation of ± 46 %.1

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

26.5

1.578 / 1.578

19.7

Column 25.0 mL/h

1.360 / 1.356

17.0

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

Because of the blocking effect of the small particles of the test item in the columns and the decreasing of the volume of the fractions the results of the two columns showed a deviation of ± 46 %. Therefore the water solubility cS of the test item was found to be in a range from 169 µg/L – 312 µg/L.


[1]During the test the volume of the fractions decreased strongly. It was assumed, that the columns were blocked by very small particles of the test item.

 

Executive summary:

The water solubility cSof the test item Disperse Yellow 79 at a temperature of 20 °C was determined according to the column elution method. It was found to be in a range of:

0.16 mg/L < cS< 0.32 mg/L

Description of key information

The water solubility cS of the test item Disperse Yellow 79 at a temperature of 20 °C was determined according to the column elution method. It was found to be in a range of:

0.16 mg/L < cS < 0.32 mg/L

Key value for chemical safety assessment

Additional information