Trimagnesium bis(orthophosphate)

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

Testing was conducted between 30 September 2009 and 30 October 2009.

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study conducted in compliance with agreed protocols, with no deviations from standard test guidelines (EU Method A.6). The substance tested is a hydrated form of the substance to be registered and therefore in accordance with 'Data Submission Manual, Part 18 - How to report substance identity in IUCLID 5 for registration under REACH' the hydrated form is considered to be different to the anhydrous form. Read-across from trimagnesium phosphate-4-hydrate to the anhydrous trimagnesium bis(orthophosphate) is justified on the basis that the addition of water is unlikely to detrimentally affect the physicochemical or (eco)toxicological profile of the substance. The reliability has been amended in accordance with 'practical guide 6: How to report read-across and categories' which states that the maximum reliability for a read-across study is 2. The study is considered to be adequate and reliable for the purpose of registration under REACH (Regulation (EC) No. 1907/2006).

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:

>= 0.042 - <= 0.049 g/L

Temp.:

20 °C

pH:

>= 8.2 - <= 8.8

Details on results:

Please see section Remarks on results including tables and figures.

Results

Preliminary test

The preliminary estimate of water solubility was 4.01 x 10^-2 g/l.

Definitive test

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

Table5.6

Solution	Mean peak area*
Standard 30.1 mg/l	3.243
Standard 30.0 mg/l	3.427
Sample 5A	2.627
Sample 5B	2.748
Sample 4A	1.947
Sample 4B	1.979
Sample 1A	1.664
Sample 1B	1.690
Standard 30.1 mg/l	3.819
Standard 30.0 mg/l	3.794
Sample 3A	1.765
Sample 3B	1.770
Sample 2A	1.696
Sample 2B	1.708
Standard 30.1 mg/l	3.865
Standard 30.0 mg/l	3.830
Sample 7A	2.302
Sample 7B	2.330
Standard 30.1 mg/l	3.845
Standard 30.0 mg/l	3.827
Sample 6A	4.278
Sample 6B	4.293

*corrected for the relevant blank

Additional test

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

Table5.7

Solution	Mean peak area
Standard 30.0 mg/l	3.758
Standard 30.6 mg/l	3.864
Sample 8A	1.632
Sample 8B	1.593
Sample 9A	1.686
Sample 9B	1.646

Overall results

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

Table 5.8

Sample Number	Time shaken at ~ 30ºC (hours)	Time equilibrated at 20ºC (hours)	Concentration (g/l)	Solution pH
1	72	24	4.18 x 10^-2	8.2
4	48	24	4.89 x 10^-2	8.8
5*	24	24	6.70 x 10^-2	8.2
8**	3½	17½	3.55 x 10^-2	9.3
9**	6½	17½	3.66 x 10^-2	8.5
2	72	24 (30°C)	3.72 x 10^-2	8.6
3	72	24 (10°C)	3.86 x 10^-2	8.5
6	72	24	0.928	7.2
7	72	24	5.00 x 10^-2	9.1

*considered to be erroneous; therefore, not used in subsequent calculations

**considered not to have reached saturation; therefore not used in subsequent conclusions

Validation

The linearity of the detector response with respect to concentration was assessed over the nominal concentration range of 0 to 100 mg/l*. This was satisfactory with a correlation coefficient of 1.000 being obtained.

*as the orthophosphate anion

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 in the range 4.18 x 10-2 to 4.89 x 10-2 g/l of solution at 20.0 ± 0.5°C, using the flask method, Method A6 Water Solubility of Commission Regulation (EC) No 440/2008 of 30 May 2008.

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 3.72 x 10-2 to 4.89 x 10-2 g/l).

An assessment of the solubility of the test material over the environmentally relevant pH range of 4 to 9 gave similar solubility results at a solution pH in the range 8.2 to 9.1; however, at a solution pH of 7.2, the water solubility of the test material was much higher. Thus, the effect of pH has been considered to have had a significant effect on the solubility of the test material.

Description of key information

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

Key value for chemical safety assessment

Water solubility:

0.048 g/L

at the temperature of:

20 °C

Additional information

The water solubility of the trimagnesium bis(orthophosphate) has been determined to be in the range 4.18 x 10-2 to 4.89 x 10-2 g/l of solution at 20.0 ± 0.5°C, using the flask method, Method A6 Water Solubility of Commission Regulation (EC) No 440/2008 of 30 May 2008. The highest recorded solubility has been chosen as the key value for the chemical safety assessment.

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 3.72 x 10-2 to 4.89 x 10-2 g/l).

An assessment of the solubility of the test material over the environmentally relevant pH range of 4 to 9 gave similar solubility results at a solution pH in the range 8.2 to 9.1; however, at a solution pH of 7.2, the water solubility of the test material was much higher. Thus, the effect of pH has been considered to have had a significant effect on the solubility of the test material.