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Diss Factsheets

Administrative data

Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Not GLP but well documented

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report date:
2010

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
EU Method A.6 (Water Solubility)
Principles of method if other than guideline:
Preliminary tests
An amount of 100 mg of the test substance was magnetically stirred with 100 ml of milliQ water for 24 hours at ambient temperature (23 ± 1 °C). After subsequent centrifugation of the solution, an insoluble fraction was observed. The test was repeated with 10 mg, instead of 100 mg, of test substance in 100 ml of milliQ water. In this case, the dissolution was complete. In the preliminary tests, the water solubility of the test substance was > 0.01 g/l. Therefore, the flask method was chosen for the main test.

Main test
Three aliquots of 250 mg of the test substance were weighed into three flasks. To each flask, 50 ml of milliQ water were added. The solutions were magnetically stirred in a thermostatic bath at 30 °C for 24, 48 or 72 hours. As a blank, 50 ml of milliQ water were stirred for 48 hours. After stirring, the solution was re-equilibrated for 24 hours in a thermostatic bath at 20 ±1 °C with occasional manual shaking. The solution was then centrifuged at ambient temperature during 5 min at 4 000 rpm. A pH measurement was performed on the soluble phase.

Because the test sample is a mixture, no specific analytical method was used to determine the solubility. Two aliquots of 20 ml of the soluble phase were dried in two steps: after a first period of evaporation at 60-70 °C under nitrogen, the residues were placed in a vacuum oven at 60 °C until constant weight.
GLP compliance:
no
Type of method:
flask method

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Two samples of the test substance were tested: SOLVCAT and Granelli CRG
Both were sampled on 2 September 2009

Results and discussion

Water solubility
Water solubility:
>= 2.9 - <= 3.1 g/L
Temp.:
20 °C
pH:
>= 7.5 - <= 8.5

Any other information on results incl. tables

The solubility results (individual and mean values) and pH measurements are summarized in the table below for the Solvcat sample. The solubility measured for the blank was < 0.1 g/l.

Stirring time (hours)

Solubility (g/l) trial 1

Solubility (g/l) trial 2

Solubility (g/l) mean value

pH

24

3.1

3.1

3.1

8.0 – 8.5

48

3.1

3.1

3.1

8.0 – 8.5

72

3.1

3.1

3.1

8.0 – 8.5

No difference is observed between the individual results, the water solubility of the test substance is 3.1 g/l.

The solubility results (individual and mean values) and pH measurements are summarized in the table below for the Granelli CRG sample. The solubility measured for the blank was < 0.1 g/l.

Stirring time (hours)

Solubility (g/l) trial 1

Solubility (g/l) trial 2

Solubility (g/l) mean value

pH

24

2.8

2.9

2.9

7.5 – 8.0

48

2.9

2.9

2.9

7.5 – 8.0

72

2.9

2.9

2.9

7.5 – 8.0
The maximum difference observed between the individual results being < 15 %, the water solubility of the test substance can be given as the average of all the individual values : 2.9 g/l.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): soluble (1000-10000 mg/L)
Based on the experimental study, which used a nominal concentration of 5 g/l, the water solubility of the substance is 2.9 - 3.1 g/l. However, it should be realised that the constituents sodium chloride (>100 g/l) and calcium sulfate (2.4 g/l) have a high water solubility, while calcium carbonate and magnesium hydroxide have a low water solubility (< 100 mg/l). When the experimental study would have been started with a higher nominal concentration most likely a higher water solubility would have been obtained (a higher amount of calcium sulfate and sodium chloride could dissolve).