reaction mass of calcium bis(dihydrogenorthophosphate) and calcium hydrogenorthophosphate

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 01 June 2010 and 03 July 2010.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results. This study is considered to be scientifically justified for use as a key 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:

7.95 g/L

Temp.:

20.5 °C

Remarks on result:

other: Expressed as dissolved calcium at a nominal loading rate of 100 g/L

Water solubility:

40.4

Temp.:

20.5 °C

Remarks on result:

other: Expressed as dissolved orthophosphate at a nominal loading rate of 100 g/L

Results

Table 3 - Preliminary test results

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

Nominal test item loading rate (g/L)		Orthophosphate concentration (g/L)	Solution pH
10		4.64	4.5
100		41.8	3.4

Definitive test

Table 4 - definitive test results

Sample #		Time shaken at ~30°C (hours)	Time equilibrated at 20°C (hours)	Concentration (g/L) [total calcium]	Concentration (g/L) [total orthophosphate]	Solution pH
1		72	24	0.738	4.19	4.5
2		72	24	7.85	40.6	3.5
3		48	24	0.588	4.13	4.4
4		48	24	7.64	41.2	3.5
5		24	24	0.908	4.37	4.3
6		24	24	8.38	39.4	3.5

Table 5 - Overall results

Nominal test item loading rate (g/L)		Concentration (g/L)
		As calcium	As orthophosphate
10		0.745	4.23
100		7.95	40.4

Conclusions:

Interpretation of results: very soluble (> 10000 mg/L)
The water solubility of the test item at 20.0±0.5°C, expressed as total dissolved calcium and orthophosphate has been determined according to the table below.

Nominal test item loading rate (g/L) Concentration (g/L)
 As calcium As orthophosphate
10 0.745 4.23
100 7.95 40.4

As the substance is a mixture of two inorganic phosphates the substance will have different soubilities in different pH's. As such it is difficult to determine an overall solubility. However the solubility will be in excess of 10g/L and therefore the test material can be regarded as very soluble.

Consequently, the results also demonstrated that water solubility may increase further should loading rate be increased.

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.

Description of key information

The water solubility of the test item at 20.0±0.5°C, expressed as total dissolved calcium and orthophosphate has been determined according to the table below.

Nominal test item loading rate (g/L)                 Concentration (g/L)

                                                                       As calcium         As orthophosphate

10                                                                          0.745                     4.23

100                                                                        7.95                     40.4

As the substance is a mixture of two inorganic phosphates the substance will have different soubilities in different pH's. As such it is difficult to determine an overall solubility. However the solubility will be in excess of 10g/L and therefore the test material can be regarded as very soluble.

Consequently, the results also demonstrated that water solubility may increase further should loading rate be increased.

Key value for chemical safety assessment

Water solubility:

10 g/L

at the temperature of:

20 °C