Tetrasodium pyrophosphate

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Testing was conducted between 02 October 2009 and 28 November 2009.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

.

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

GLP compliance:

yes (incl. QA statement)

Remarks:

Date of inspection: 2009-09-15 Date of Signature: 2009-11-26

Type of method:

flask method

Remarks:

The determination was carried out using the flask method, Method A6 Water Solubility of Commission Regulation (EC) No 440/2008 of 30 May 2008.

Water solubility:

58.5 g/L

Temp.:

20 °C

pH:

9.9

Remarks on result:

other: For effect of temperature and pH, see conclusion

Details on results:

Please see section Remarks on results including tables and figures.

Results

Preliminary test

The mean peak areas relating to the standard and sample solutions are shown in the following table:

Table4.6

Solution	Mean peak area
Standard 30.8 mg/l	4.431
Standard 30.8 mg/l	4.257
Sample 1	5.324
Sample 2	5.353
Sample 3	5.477

The concentration (g/l) of test material in the sample solutions is shown in the following table:

Table 4.7

Sample Number	Time shaken at ~ 30ºC (hours)	Time equilibrated at 20ºC (hours)	Concentration (g/l)	Solution pH
1	20	3	57.7	10.1
2	20	3	58.0	9.3
3	20	3	59.4	9.3

As the results indicated final solution pH and solubility results for the samples prepared in the pH 4 and pH 9 buffer solutions similar to those obtained using unbuffered water, it can be anticipated that the water solubility of the test material would be constant over the pH range 4 to 9, essentially due to the low buffering activities seen in the environment.

Definitive test

The mean peak areas relating to the standard and sample solutions are shown in the following table:

Table4.8

Solution	Mean peak area
Standard 30.1 mg/l	4.199
Standard 30.1 mg/l	3.986
Sample 4A	7.043
Sample 4B	7.097
Sample 5A	3.705
Sample 5B	3.658
Sample 6A	5.139
Sample 6B	5.183
Sample 7A	5.276
Sample 7B	5.211
Sample 8A	5.236
Sample 8B	5.177

The concentration (g/l) of test material in the sample solutions is shown in the following table:

Table 4.9

Sample Number	Time shaken at ~ 30ºC (hours)	Time equilibrated at 20ºC (hours)	Concentration (g/l)	Solution pH
4	72	24 [30°C]	79.5	9.8
5	72	24 [10°C]	41.4	9.8
6	72	24	58.0	9.9
7	48	24	58.9	9.9
8	24	24	58.5	9.9

Validation

The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 0 to 50 mg/l*. * as the pyrophosphate anion. This was satisfactory with a correlation coefficient of 0.999 being obtained. This work was performed as part of Harlan Laboratories Ltd Project Number 2920/0039.

Conclusions:

Interpretation of results (migrated information): very soluble (> 10000 mg/L)
The water solubility of the test material has been determined. The results are shown in the table within the Executive Summary Section.
Overall, the effect of temperature over the range 10 to 30°C has been considered to have had a significant influence on the solubility of the test material.
An assessment of the solubility of the test material over the environmentally relevant pH range of 4 to 9 gave final solution pH and solubility results similar to those obtained using unbuffered water. Thus, it can be anticipated that the water solubility of the test material over the pH range 4 to 9 would be constant, essentially due to the low buffering activities seen in the environment.
This study is conducted according to an appropriate guideline and under the conditions of GLP and therefore the study is considered to be acceptable and to adequately satisfy both the guideline requirement and the regulatory requirement as a key study for this endpoint.

Executive summary:

Method

The determination was carried out using the flask method, Method A6 Water Solubility of Commission Regulation (EC) No 440/2008 of 30 May 2008.

Conclusion

The water solubility of the test material has been determined. The results are shown in the following table:

Test temperature	Water solubility (g/l)	Typical solution pH
30.0±0.5°C	79.5	9.8
20.0±0.5°C	58.5	9.9
10.0±0.5°C	41.4	9.8

Overall, the effect of temperature over the range 10 to 30°C has been considered to have had a significant influence on the solubility of the test material.

An assessment of the solubility of the test material over the environmentally relevant pH range of 4 to 9 gave final solution pH and solubility results similar to those obtained using unbuffered water. Thus, it can be anticipated that the water solubility of the test material over the pH range 4 to 9 would be constant, essentially due to the low buffering activities seen in the environment.

Description of key information

The water solubility tetrasodium pyrophosphate was determined according to EU Method A.6 (Water solubility) and under the conditions of GLP

Key value for chemical safety assessment

Water solubility:

58.5 g/L

at the temperature of:

20 °C