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EC number: 232-221-5 | CAS number: 7790-76-3
Water solubility
Administrative data
Link to relevant study record(s)
- Endpoint:
- water solubility
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Study period:
- 12 Oct - 19 Dec 2009
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: GLP - Guideline study
- Qualifier:
- according to guideline
- Guideline:
- EU Method A.6 (Water Solubility)
- Deviations:
- no
- GLP compliance:
- yes (incl. QA statement)
- Type of method:
- flask method
- Water solubility:
- < 0.255 mg/L
- Temp.:
- 20 °C
- pH:
- 6.3 - 6.5
- Details on results:
- Please see section Any other information on results incl. tables.
- Conclusions:
- Interpretation of results (migrated information): slightly soluble (0.1-100 mg/L)
The water solubility of the test material has been determined to be less than 2.55 x 10-4 g/l of solution at 20.0 ± 0.5°C.
The initial solution pH was shown to significantly influence solubility of the test material. When using an identical initial saturation period of 72 hours, the use of the pH 4 buffer solution significantly increased the resulting equivalent test material concentration dissolved (when compared to unbuffered water) to 3.75 x 10-3 g/l at 20.0 ± 0.5°C (at a final solution pH of 4.2), whereas the use of the pH 9 buffer solution increased the resulting equivalent test material concentration to 4.29 x 10-4 g/l at 20.0 ± 0.5°C (at a final solution pH of 8.9). Therefore, although the maximum observed solubility was
3.75 x 10-3 g/l (at a final solution pH of 4.2), the water solubility of the test material may increase further in cases where additional buffering capacity exists. - Executive summary:
Method
The determination was carried out using the flask method, Method A6 Water Solubility ofCommission Regulation (EC) No 440/2008 of 30 May 2008.
Conclusion
The water solubility of the test material has been determined to be less than 2.55 x 10-4 g/l of solution at 20.0±0.5°C.
The initial solution pH was shown to significantly influence solubility of the test material. When using an identical initial saturation period of 72 hours, the use of the pH 4 buffer solution significantly increased the resulting equivalent test material concentration dissolved (when compared to unbuffered water) to 3.75 x 10-3g/l at 20.0±0.5°C (at a final solution pH of 4.2), whereas the use of the pH 9 buffer solution increased the resulting equivalent test material concentration to 4.29 x 10-4g/l at 20.0±0.5°C (at a final solution pH of 8.9). Therefore, although the maximum observed solubility was
3.75 x 10-3g/l (at a final solution pH of 4.2), the water solubility of the test material may increase further in cases where additional buffering capacity exists.
Reference
Results
Preliminary test
The mean peak areas relating to the standard and sample solutions are shown in the following table:
Table 4
Solution |
Mean peak area |
Standard 30.3 mg/l |
4.693 |
Standard 30.1 mg/l |
4.729 |
Sample 1 |
0.105 |
Standard 30.1 mg/l |
4.237 |
Standard 30.7 mg/l |
4.469 |
Sample 2A |
0.496 |
Sample 2B |
0.486 |
Sample 3A |
0.103 |
Sample 3B |
0.109 |
The concentration (g/l) of test material in the sample solutions is shown in the following table:
Table 5
Sample Number |
Time shaken at ~ 30 ºC (hours) |
Time equilibrated at 20 ºC (hours) |
Concentration (g/l) |
Solution pH |
1 |
25 ¾ |
25 ¼ |
1.97 x 10-3 |
7.2 |
2 |
24 |
25 ½ |
≤9.99 x 10-3 |
4.2 |
3 |
24 |
25 ½ |
2.16 x 10-3 |
8.8 |
Definitive test
The mean peak areas relating to the standard and sample solutions are shown in the following table:
Table 6
Solution |
Mean peak area |
Standard 30.2 mg/l |
4.482 |
Standard 30.0 mg/l |
4.435 |
Sample 4A |
<1.30 x 10-2 |
Sample 4B |
<1.30 x 10-2 |
Sample 5A |
<1.30 x 10-2 |
Sample 5B |
<1.30 x 10-2 |
Sample 6A |
0.189 |
Sample 6B |
0.192 |
Standard 30.2 mg/l |
4.538 |
Standard 30.0 mg/l |
4.441 |
Sample 7A |
<1.30 x 10-2 |
Sample 7B |
<1.30 x 10-2 |
Sample 8A |
<1.30 x 10-2 |
Sample 8B |
<1.30 x 10-2 |
Sample 9A |
<1.30 x 10-2 |
Sample 9B |
<1.30 x 10-2 |
Standard 31.8 mg/l |
4.432 |
Standard 15.1 mg/l* |
2.012 |
Sample 10A |
2.15 x 10-2 |
Sample 10B |
1.86 x 10-2 |
* See Discussion in Overall remarks and attachments section
The concentration (g/l) of test material in the sample solutions is shown in the following table:
Table 7
Sample Number |
Time shaken at ~ 30 ºC (hours) |
Time equilibrated at 20 ºC (hours) |
Concentration (g/l) |
Solution pH |
4 |
72 |
24 [10 ºC] |
<2.56 x 10-4 |
6.3 |
5 |
72 |
24 [30 ºC] |
<2.56 x 10-4 |
6.3 |
6 |
72 |
24 |
3.75 x 10-3 |
4.2 |
7 |
72 |
24 |
<2.55 x 10-4 |
6.3 |
8 |
48 |
24 |
<2.55 x 10-4 |
6.5 |
9 |
24 |
24 |
<2.55 x 10-4 |
6.5 |
10 |
72 |
24½ |
4.29 x 10-4 |
8.9 |
Mean unbuffered water result (at 20.0 ± 0.5°C): <2.55 x 10-4g/l.
Validation
The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 0 to 125 mg/l*. * as the pyrophosphate anion. This was satisfactory with a correlation coefficient of 1.000 being obtained. This work was performed as part of Harlan Laboratories Ltd Project Number 2920/0050.
Description of key information
Water solubility: < 0.255 mg/L at 20.0 ± 0.5°C (EU Method A.6, GLP)
Key value for chemical safety assessment
- Water solubility:
- 0.255 mg/L
- at the temperature of:
- 20 °C
Additional information
The water solubility of dicalcium pyrophosphate was determined using the flask method in a study conducted according to EU Method A.6 under GLP conditions (Walker and O’Connor, 2010). The water solubility of the test material was determined to be less than 0.255 mg/L at 20 ± 0.5 °C (final solution pH 6.3-6.5).
The initial solution pH was shown to significantly influence solubility of the test material. When using an identical initial saturation period of 72 hours, the use of the pH 4 buffer solution significantly increased the resulting equivalent test material concentration dissolved (when compared to unbuffered water) to 3.75 mg/L at 20.0 ± 0.5°C (at a final solution pH of 4.2), whereas the use of the pH 9 buffer solution increased the resulting equivalent test material concentration to 0.429 mg/L at 20.0 ± 0.5°C (at a final solution pH of 8.9). Therefore, although the maximum observed solubility was 3.75 mg/L (at a final solution pH of 4.2), the water solubility of the test material may increase further in cases where additional buffering capacity exists.
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