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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 14/02/2012 to 24/08/2012
Reliability:
2 (reliable with restrictions)
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 should be used, that the individual results from the three flask should not differ by more than 15.0% of the average. In this study, the three samples did not differ by more than 15.9% of the average. This valud is only slightly higher than the requested 15.0%. This report is well documented and should be considered reliable with restrictions.
Reason / purpose for cross-reference:
reference to same study
Reason / purpose for cross-reference:
reference to other study
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 105 (Water Solubility)
Deviations:
no
Qualifier:
equivalent or similar to guideline
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. QA statement)
Remarks:
2012-07-18
Type of method:
other: Slow stirring flask method
Water solubility:
10.66 mg/L
Temp.:
20.4 °C
pH:
5
Remarks on result:
other: The average value of test substance 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 may not have been completely reached within 3 days. However, concentrations from the 3 following samples did not differ by more than 15.9 % of the average. This value is only slightly higher than the requested 15.0 %.
The average value of the test substance water solubility was calculated as the mean of the 3 last values obtained during approximately 3 days. Thus, it can be concluded that the water solubility of the test substance is approximately 10.66 mg/L but may be as high as 12.37 mg/L.

Table 4.8/03: Water solubility results

 

TERT-BUTYL CUMYL PEROXIDE, mg/L

 

 

Time, h

 

 

0

5

24

 

29

48

72

 

Flask A

 

 

< DL

5.3

9.8

 

9.3

10.5

11.5

 

Flask B

 

 

< DL

4.7

9.5

 

9.0

10.1

12.5

 

Flask C

 

 

< DL

4.9

9.8

 

10.0

10.0

13.1

 

Average

 

 

-

4.97

9.7

 

9.43

10.2

12.37

% deviation from the 10.66 mg/L average

 

-

-

9.0

11.5

4.3

15.9

Conclusions:
Interpretation of results (migrated information): slightly soluble (0.1-100 mg/L)
The water solubility of the test substance is approximately 10.66 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 substance.

In a first step, a Column Elution method (according to OECD Guideline 105) was performed. However, the concentrations measured decreased during the first hours and finally passed under the detection limit (DL) after one night. The reason for the decrease of the chemical concentration and its disappearance after 23 hours could not be resolved. These results showed that the column method cannot be used for the measurement of the water solubility of the substance. It was decided to stop this experiment and use an alternative method: a slow-stir protocol derived from the OECD Guideline 123 Slow Stirring met

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 (697 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/water, samples are analyzed using HPLC/UV. The Detection Limit of the method (DL) is 0.015 mg/L and the Quantification Limit is 0.051 mg/L.

During the analysis, the temperature was 20.4°C and the mean value or pH was 5.0. The equilibrium may not have been completely reached within 3 days. However, concentrations from the 3 following samples did not differ by more than 15.9 % of the average. This value is only slightly higher than the requested 15.0 %. The average value of the test substance water solubility was calculated as the mean of the 3 last values obtained during approximately 3 days. Thus, it can be concluded that the water solubility of the test substance is approximately 10.66 mg/L but may be as high as 12.37 mg/L.

Description of key information

Method derived from the OECD Guideline 105 and 123, GLP, key study, validity 2: Water solubility = 10.66 mg/l at the temperature of 20°C.

Key value for chemical safety assessment

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

Additional information

One key study is available to assess the water solubility of the substance. This study was performed according to a method derived from the OECD Guideline 105 and 123, with GLP statement.

In a first step, a Column Elution method (according to OECD Guideline 105) was performed. However, the concentrations measured decreased during the first hours and finally passed under the detection limit (DL) after one night, showing that this method cannot be used for the measurement of the water solubility of the substance. It was decided to stop this experiment and use an alternative method: a slow-stir protocol derived from the OECD Guideline 123 Slow Stirring method. 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 was taken into account: the individual results from the three flasks should not differ by more than 15% of the average.

During the analysis, the temperature was 20.4°C and the mean value or pH was 5.0.

The equilibrium may not have been completely reached within 3 days. However, concentrations from the 3 following samples did not differ by more than 15.9 % of the average. This value is only slightly higher than the requested 15.0 %. The average value of the test substance water solubility was calculated as the mean of the 3 last values obtained during approximately 3 days. Thus, it can be concluded that the water solubility of the test substance is approximately 10.66 mg/L but may be as high as 12.37 mg/L.