Disodium dihydrogenpyrophosphate

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 06 October 2009 and 04 December 2009.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

no

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:

EXAMPLE: 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:

170 g/L

Temp.:

20 °C

pH:

>= 3.8 - <= 3.9

Details on results:

Please see section Remarks on results including tables and figures.

Results

Preliminary test

The preliminary estimates of water solubility in un-buffered glass double-distilled water, pH 4 and pH 9 buffered solutions are shown in the following table:

Sample Number	Test Media	Time shaken at ~ 30ºC (hours)	Time equilibrated at 20ºC (hours)	Concentration (g/l)	Solution pH
A	glass double - distilled water	19	3	175	3.66
B	pH 4 buffer	19	3	174	3.65
C	pH 9 buffer	19	3	172	3.67

 

Definitive test

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

Solution	Mean peak area
Standard 29.9 mg/l	4.550
Standard 29.9 mg/l	4.504
Sample 1A	4.053
Sample 1B	4.049
Sample 2A	3.971
Sample 2B	3.992
Sample 3A	4.067
Sample 3B	4.094
Standard 29.9 mg/l	4.562
Standard 29.9 mg/l	4.519
Sample 4A	4.010
Sample 4B	4.040
Sample 5A	4.083
Sample 5B	4.149

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

Sample Number	Test Media	Time shaken at ~ 30ºC (hours)	Time equilibrated at 20ºC (hours)	Concentration (g/l)	Solution pH
1	glass double-distilled water	24	20.0	171	3.84
2	glass double-distilled water	48	20.0	168	3.82
3	glass double-distilled water	72	20.0	172	3.92
4	glass double-distilled water	72	10.0	169	3.93
5	glass double-distilled water	72	30.0	173	3.74

Overall result (mean of samples 1 to 3): 170 g/l at 20.0 ± 0.5°C

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 pyrophosphate anion). This was satisfactory with a correlation coefficient of 0.999 being obtained.

Conclusions:

Interpretation of results (migrated information): very soluble (> 10000 mg/L)
The water solubility of the test material has been determined to be 170 g/l of solution at 20.0 ± 0.5°C in un-buffered glass double-distilled water, resulting in sample solution pH’s of approximately 3.8 to 3.9.
This study is conducted according to the appropriate guidelines (EU ) 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 ofCommissionRegulation (EC) No 440/2008 of 30 May 2008.

Conclusion

The ion chromatography method applied directly quantified the dissolved pyrophosphate content of each sample solution and these have been corrected to equivalent test material concentrations based on the theoretical pyrophosphate content of the test material.

The water solubility of the test material has been determined to be 170 g/l of solution at 20.0 ± 0.5°C in un-buffered glass double-distilled water, resulting in sample solution pH’s of approximately 3.8 to 3.9.

The effect of temperature over the range 10 to 30°C has been considered not to have had a significant influence on the solubility of the test material (range 169 to 173 g/l). 

The solubility of the test material over the environmentally relevant pH range of 4 to 9 gave solubility results and final solution pH’s similar to those obtained using unbuffered water (range 172 to 175 g/l). 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 of disodium dihydrogenpyrophosphate was determined according to EU Method A.6 (Water solubility) and under the conditions of GLP. 

Key value for chemical safety assessment

Water solubility:

170 g/L

at the temperature of:

20 °C

Additional information

The water solubility of the test material has been determined to be 170 g/l of solution at 20.0 ± 0.5°C in un-buffered glass double-distilled water, resulting in sample solution pH’s of approximately 3.8 to 3.9.