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Physical & Chemical properties

Water solubility

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Reference
Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Testing was conducted between 30 September 2009 and 17 November 2009.
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 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.
Qualifier:
according to
Guideline:
EU Method A.6 (Water Solubility)
Deviations:
no
GLP compliance:
yes (incl. certificate)
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:
0.578 g/L
Temp.:
20 °C
pH:
>= 7.4 - <= 7.6
Details on results:
Please see section Remarks on results including tables and figures.

           

SEE ATTACHMENT FOR EXAMPLES OF TYPICAL CHROMATOGRAPHY

Preliminary testing:

Un-buffered glass double-distilled water

The preliminary estimate of water solubility, as equivalent test material concentration, was 0.870 g/l, with a final sample solution pH of 7.7.

pH 4 buffer solution

The preliminary estimate of water solubility, as equivalent test material concentration, was 1.48 g/l, with a final sample solution pH of 6.6. Calculations were performed from the sample solutions diluted by a factor of 50 for analysis.

pH 9 buffer solution

The preliminary estimate of water solubility, as equivalent test material concentration, was 0.782 g/l, with a final sample solution pH of 7.9. Calculations were performed from the sample solutions diluted by a factor of 10 for analysis.

 Definitive test:

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

Un-buffered glass double-distilled water

Solution

Area

Standard 42.0 mg/l

3.195

Standard 43.8 mg/l

3.328

Matrix blank

none detected

Sample 1A

1.926

Sample 1B

1.934

Sample 2A

1.977

Sample 2B

1.983

 

Un-buffered glass double-distilled water (continued)

Solution

Area

Standard 42.0 mg/l

3.272

Standard 43.8 mg/l

3.388

Sample 3A

2.034

Sample 3B

2.037

Sample 4A

1.953

Sample 4B

1.968

Sample 5A

2.042

Sample 5B

2.039

pH 4 buffer solution

Solution

Area

Standard 84.0 mg/l

6.673

Standard 87.6 mg/l

6.952

Matrix blank

none detected

Sample 1A

3.926

Sample 1B

3.951

pH 9 buffer solution

Solution

Area

Standard 42.0 mg/l

3.298

Standard 43.8 mg/l

3.413

Matrix blank

none detected

Sample 1A

2.858

Sample 1B

2.862

 


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

Un-buffered glass double-distilled water

Sample
 Number

Time Shaken at

~ 30ºC (hours)

Equilibration Temperature (°C)

Equilibration Time (hours)

Equivalent Test Material Concentration
(g/l)

Solution pH

1

24

20

24

0.567

7.6

2

48

20

24

0.582

7.5

3

72

20

24

0.586

7.5

4

72

30

24

0.564

7.4

5

72

10

24

0.587

7.5

Mean concentration:       0.578 g/l at 20.0 ± 0.5ºC (samples 1 to 3 inclusive only)
Range:                             0.567 to 0.586 g/l (samples 1 to 3 inclusive only)

pH 4 buffer solution

Sample
 Number

Time Shaken at

~ 30ºC (hours)

Equilibration Temperature (°C)

Equilibration Time (hours)

Equivalent Test Material Concentration
(g/l)

Solution pH

1

72

20

24

1.11

6.8

pH 9 buffer solution

Sample
 Number

Time Shaken at

~ 30ºC (hours)

Equilibration Temperature (°C)

Equilibration Time (hours)

Equivalent Test Material Concentration
(g/l)

Solution pH

1

72

20

24

0.817

7.1

Conclusions:
Interpretation of results (migrated information): moderately soluble (100-1000 mg/L)
The water solubility of the test material has been determined to be 0.578 g/l of solution at 20.0 ± 0.5°C in un-buffered glass double-distilled water, resulting in sample solution pH’s in the range 7.4 to 7.6.

Description of key information

Water solubility: 0.578 g/L (EU Method A.6; GLP). 

Key value for chemical safety assessment

Water solubility:
0.578 g/L
at the temperature of:
20 °C

Additional information

The water solubilty of magnesium hydrogenorthophosphate has been determined to be 0.578 g/L, using the flask method, Method A.6 Water solubility.