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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:
from 2018-09-27 to 2019-05-08
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 105 (Water Solubility)
Deviations:
yes
Remarks:
It was technical not feasible to establish a substance specific analytical method. Therefore, an unspecific method based on the total silicon content was used.
GLP compliance:
yes (incl. QA statement)
Type of method:
flask method
Key result
Water solubility:
7.4 mg/L
Conc. based on:
element
Loading of aqueous phase:
0.1 mg/L
Incubation duration:
24 h
Temp.:
20 °C
pH:
>= 6.41 - <= 6.9
Details on results:
The repeatability of the determination was < 15 % and thus within the range required by the guidelines. All the time a clear aqueous phase was observed in all of the vessels, the test item stuck to the wall

Sampling time

Measured concentrationofTest Item
(mg/L )

Measured pH

Test vessels

Mean

After 24 h

7.37

7.5

6.57

7.56

6.83

7.66

6.42

After 48 h

6.54

7.9

6.53

8.39

6.45

8.75

6.41

After 72 h

7.00

6.9

6.83

7.12

6.88

6.44

6.90

Solubility ofthe test item (mg/L)
with the 95 % confidence interval:

7.4 ± 1.3

-

RSD%:

7

-

Conclusions:
The water solubility of the test item was determined to be 7.4 ± 1.3 mg/L (95 % confidence interval) at 20 ± 0.5 °C using the shake-flask method.
Executive summary:

The water solubility was determined according to OECD 105 using the shake flask method with ICP-OES analysis. It was technical not feasible to establish a substance specific analytical method. Therefore, an unspecific method based on the total silicon content was used. About 6-8 mg test substance was weighed into 100 mL stoppered Erlenmeyer flasks (nine parallels) according to the estimated solubility based on the Preliminary Test. After the addition of 100 mL ultra-pure water, the flasks were agitated at 30 °C. After one day, three of the vessels were removed and re-equilibrated at 20 °C for 24 hours. The content of the vessel was then centrifuged at 20 °C and the concentration in the clear aqueous phase was determined by ICP-OES. The other flasks were treated similarly after initial equilibration at 30 °C for two and three days, respectively. The samples were diluted before the analysis (two parallel dilutions). The pH of each sample was recorded. The water solubility of the test substance was determined to be 7.4 ± 1.3 mg/L (95 % confidence interval) at 20 °C ± 1 °C (pH 6.5 to 6.9).

Description of key information

The water solubility of the test item was determined to be 7.4 ± 1.3 mg/L (95 % confidence interval) at 20 ± 0.5 °C using the shake-flask method.

Key value for chemical safety assessment

Water solubility:
7.4 mg/L
at the temperature of:
20 °C

Additional information

The water solubility was determined according to OECD 105 using the shake flask method with ICP-OES analysis. The substance is not stable in water. Its technical function is to hydrolyse and/or polymerize rapidly upon contact with water. Thus, it was technically not feasible to develop and validate analytical method suitable to detect the substance in water. Therefore, an unspecific method based on the total silicon content was used. About 6-8 mg test substance was weighed into 100 mL stoppered Erlenmeyer flasks (nine parallels) according to the estimated solubility based on the Preliminary Test. After the addition of 100 mL ultra-pure water, the flasks were agitated at 30 °C. After one day, three of the vessels were removed and re-equilibrated at 20 °C for 24 hours. The content of the vessel was then centrifuged at 20 °C and the concentration in the clear aqueous phase was determined by ICP-OES. The other flasks were treated similarly after initial equilibration at 30 °C for two and three days, respectively. The samples were diluted before the analysis (two parallel dilutions). The pH of each sample was recorded. The water solubility of the test substance was determined to be 7.4 ± 1.3 mg/L (95 % confidence interval) at 20 °C ± 1 °C (pH 6.5 to 6.9).