Tetrapotassium 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 04 February 2010.

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: 15 September 2009 Date of Signature: 26 November 2009

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:

>= 67.2 - <= 69.9 other: % w/w

Temp.:

20 °C

pH:

10.6

Details on results:

Please see section Remarks on results including tables and figures.

Results

Preliminary test

The sample concentrations, observations and solution pH are shown in the following table:

Sample Identity	Concentration (% w/w)	Observations	Solution pH
1	10.1	Clear colourless solution, test material completely dissolved.	10.7
2	25.0	Clear colourless solution, test material completely dissolved.	10.8
3	40.0	Clear colourless solution, test material completely dissolved.	10.7
4	60.0	Clear colourless solution, test material completely dissolved.	10.9
5	74.9	Test material not dissolved fully; excess in solution.	*
6	65.0	Slightly viscous, clear colourless solution, no excess undissolved test material.	12.2
7	69.9	Two-phase system, comprising a slightly viscous, clear colourless liquid and white powder, i.e. excess undissolved test material.	*

Preliminary results:  Greater than 65.0 % w/w but less than 69.9 % w/w.

*unable to record due to the physical state of the sample

                  

Definitive test

The sample concentrations, observations and solution pH are shown in the following tables:

Sample Identity	Concentration (% w/w)	Observations	Solution pH
8	65.5	Test material fully dissolved.	10.5
9	67.0	Test material not fully dissolved.	*
10	69.8	Test material not fully dissolved.	*
11	67.2	Test material fully dissolved.	10.6
12	64.2	Test material fully dissolved.	10.8
13	67.2	Test material fully dissolved.	10.9
14	69.6	Test material not fully dissolved.	*
15	64.8	Test material fully dissolved.	10.8
16	64.6	Test material fully dissolved.	10.9

Overall results:          30°C: In the range 65.5 to 67.0 % w/w
                                  20°C: In the range 67.2 to 69.9 % w/w
                                  10°C: In the range 67.2 to 69.6 % w/w

*unable to record due to the physical state of the sample

Conclusions:

Interpretation of results (migrated information): very soluble (> 10000 mg/L)
The water solubility of the test material has been determined to be in the range 67.2 to 69.9 % w/w at 20.0 ± 0.5°C.
The effect of temperature over the range 10 to 30°C has been considered not to have had a significant influence on the observed solubility of the test material.
Additionally, an assessment of the solubility of the test material over the environmentally relevant pH range of 4 to 9 gave observed solubilities and final solution pH’s 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 method and under the conditions of GLP and therefore the study is considered to be acceptable and to adequately satisfy the regulatory requirement as a key study for this endpoint.

Executive summary:

Method

The determination was carried out by visual assessment using a flask method, based on 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 to be in the range 67.2 to 69.9 % w/wat 20.0±0.5°C.

The effect of temperature over the range 10 to 30°C has been considered not to have had a significant influence on the observed solubility of the test material.

Additionally, an assessment of the solubility of the test material over the environmentally relevant pH range of 4 to 9 gave observed solubilities and final solution pH’s 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 of the test material has been determined to be in the range 67.2 to 69.9 % w/w at 20.0 ± 0.5°C.

Key value for chemical safety assessment

Water solubility:

10 000 mg/L

at the temperature of:

20 °C