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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:
19-03-2010 to 15-06-2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 105 (Water Solubility)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.6 (Water Solubility)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
column elution method
Specific details on test material used for the study:
- Name: Magnesium hydroxide
- Batch no. 20BR0026
- CAS No.: 1309-42-8
- Purity: 99.9 %
- Expiry date: 31 January 2012
- Storage Room Temp. in the dark
Water solubility:
1.59 mg/L
Temp.:
20.3 °C
pH:
8.3
Remarks on result:
other: Flow rate: 24 ml/h
Water solubility:
1.98 mg/L
Temp.:
20.3 °C
pH:
8.3
Remarks on result:
other: Flow rate: 12 ml/h
Key result
Water solubility:
1.78 mg/L
Temp.:
20.3 °C
pH:
8.3
Remarks on result:
other: Mean
Details on results:
The water solubility of a test substance is specified by the saturation mass concentration of the test substance in water at a given temperature and is expressed in g/l.

The coefficient of variation (CV) (n=5) was < 30 % at both flow rates. The maximum difference (MD) on water solubility was also < 30 %. Therefore, the water solubility of the test substance was given as the mean value of the measurements at both flow rates. No undissolved particles were detected in the eluates using the Tyndall effect. A small test substance response, with a maximum contribution of 5.1 % to the sample concentrations was measured in the blank.

Preliminary results:

The content of the test substance dissolved in the water sample was < 10 -2 g/l (8.75 mg/l). Therefore the column elution method was selected.

Main study:

The results for the samples taken at a flow rate of 12 and 24 ml/hour are given in Table 1.

Table 1. Water solubility of the test substance

Flow rate (ml/h)

Sample no.

Concentration analysed

pH

Individual (10-3g mg/l)

Individual (10-3g TS/l)

Mean of concentration obtained at one flow rate

Mean of concentrations obtained at two flow rates

Mean (10-3g TS/l)

CV (%)

Mean (10-3g TS/l)

MD (%)

24

1

0.672

1.61*

1.59

1.5

1.78

22

8.3

2

0.661

1.58*

3

0.652

1.52*

4

0.670

1.61*

5

0.679

1.63*

6

0.671

1.61

7

0.654

1.57

8

0.655

1.57

9

0.654

1.57

10

0.673

1.61

 12

1

1.06

2.54*

1.98

3.1

8.3

2

0.975

2.34*

3

0.887

2.13*

4

0.867

2.08*

5

0.840

2.01*

6

0.861

2.07

7

0.838

2.01

8

0.794

1.90

9

0.821

1.97

10

0.815

1.95

* Since a decreasing concentration was used to measure the first 5 samples, particularly at the flow rate of 12 ml/min, only samples 6-10 were used for calculation of the water solubility. This procedure is described in the water solubility guidelines.

Conclusions:
Interpretation of results: slightly soluble (0.1-100 mg/L)
The column elution method was chosen for the determination of the water solubility of magnesium hydroxide. The water solubility of the test substance at 20 °C was 1.78 x 10^-3 g total solids/l. The pH of the saturated aqueous samples was 8.3.
Executive summary:

In a GLP guideline study according to OECD 105 and EEC A.6, the water solubility of Magnesium hydroxide was investigated.

Using the column elution method, a water solubility of 1.78 x 10^-3 g total solids/l. was determined at 20 °C using a validated ICP-MS method.

Description of key information

The water solubility of the test substance at 20 °C was 1.78 x 10^-3 g total solids/l. The pH of the saturated aqueous samples was 8.3.

Key value for chemical safety assessment

Water solubility:
1.78 mg/L
at the temperature of:
20 °C

Additional information

The column elution method was chosen for the determination of the water solubility of Magnesium hydroxide. The water solubility of the test substance at 20 °C was 1.78 x 10-3 g total solids/l. The pH of the aqueous samples was 8.3.