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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 06/07/2011 to 25/10/2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
This study was performed according to a method derived from the OECD Guideline 105 and 123 with GLP statement. As no validity criteria were defined for this method, the most stringent criterion from the flask method is used and is fulfilled. This report is well documented and no deviations were observed.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 105 (Water Solubility)
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
other: OECD Guideline 123 (Slow Stirring method, Octanol/Water Partition Coefficient)
Deviations:
not applicable
Principles of method if other than guideline:
The water solubility of the test item was assessed according to a method derived from the OECD Guideline 105 and 123, using a slow-stir protocol.
GLP compliance:
yes (incl. certificate)
Remarks:
2012-07-18
Type of method:
other: Slow stirring flask method
Key result
Water solubility:
5.39 mg/L
Temp.:
20.3 °C
pH:
5.3
Remarks on result:
other: The average value of test item water solubility was calculated as the mean of the 3 last values obtained during approximately 3 days.
Details on results:
See table 4.8/03 in "Any other information on results incl. tables".
The equilibrium was reached after approximately 1 day, as concentrations from the 3 following samples did not differ by more than 15% of the average. The average value of test item water solubility was calculated as the mean of the 3 last values obtained during approximately 3 days.

Table 4.8/03: Water solubility results

Sample

1

2

3

Time

24 h

48 h

72 h

Flask A

5.0

5.0

5.5

Flask B

5.6

5.3

5.3

Flask C

5.7

5.2

5.9

Average

5.43

5.17

5.57

% derivation from the 5.39 mg/L average

0.7

4.1

3.3

Conclusions:
Interpretation of results (migrated information): slightly soluble (0.1-100 mg/L)
The water solubility of the test item is 5.39 mg/L.
Executive summary:

This study was performed according to a method derived from the OECD Guideline 105 and 123, with GLP statement, to assess the water solubility of the test item.

In a first step, a Column Elution method (according to OECD Guideline 105) was performed. However, the concentrations measured were not stable over time. Concentration of the test item was strongly decreased after 24 hours. This is attributed to relatively rapid abiotic degradation of this substance. It was decided to stop the experimentation and to use a slow-stir protocol derived from the OECD Guideline 123 Slow Stirring method.

This method uses a special temperature controlled 800 mL glass-jacketed test vessels with a sampling tap at the lower end and a magnetic stir bar at their bottom. Three flasks were used for the test. A volume of 650 mL of ultrapure water at 20°C was first poured into the flasks and 650 mg (793 µL) of the test item was gently added at the surface of water into each flask. The solution was stirred, with a magnetic stir barer at a speed which did not allow an emulsion to be formed. A speed of approximately 200 rpm was set up in order to create a vortex depth of around 0.5 cm. Samples were taken from each flask over a 3 day period, with prior elimination of 5 to 10 mL of test solution at each time point in order to rinse the tap before sampling. As the OECD Guideline does not describe this modification, no validity criteria are described. For this reason, the most stringent criterion from the flask method, that the individual results from the three flask should not differ by more than 15% of the average.

For the chemical analysis, a substance specific method was performed. After being diluted in acetonitrile and methanol, samples of the test item in water are analyzed using high-pressure liquid chromatography coupled with mass spectrometry (HPLC/MS). The Detection Limit of the method (DL) is 0.13 mg/L and the Quantification Limit is 0.42 mg/L.

During the analysis, the temperature was 20.3°C and the mean value or pH was 5.3. The equilibrium was reached after approximately 1 day, as concentrations from the 3 following samples did not differ by more than 15% of the average. The average value of test item water solubility was calculated as the mean of the 3 last values obtained during approximately 3 days.

In conclusion, the water solubility of the test item is 5.39 mg/L.

Description of key information

The water solubility of OO-t-butyl-O-(2-ethylhexyl)monoperoxycarbonate was determined to be 5.39 mg/L.

Key value for chemical safety assessment

Water solubility:
5.39 mg/L
at the temperature of:
20.3 °C

Additional information

In a first step, a Column Elution method (according to OECD Guideline 105) was performed. However, the concentrations measured were not stable over time. Concentration of the test item was strongly decreased after 24 hours. This is attributed to relatively rapid abiotic degradation of this substance. It was decided to stop the experimentation and to use a slow-stir protocol derived from the OECD Guideline 123 Slow Stirring method which did not allow an emulsion to be formed. The study was performed in accordance with GLP requirements.

In conclusion, the water solubility of OO-t-butyl-O-(2-ethylhexyl)monoperoxycarbonate is 5.39 mg/L.