Registration Dossier

Administrative data

Endpoint:
hydrolysis
Data waiving:
study technically not feasible
Justification for data waiving:
the study does not need to be conducted because the substance is highly insoluble in water
Cross-reference
Reason / purpose:
data waiving: supporting information
Reference
Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
20 Nov 2018 - 20 Dec 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 105 (Water Solubility)
Deviations:
not specified
GLP compliance:
yes
Type of method:
flask method
Specific details on test material used for the study:
Chemical name: Magnesium potassium fluoride silicate (Mg2.7K0.7Si4O10F2)
Previously known as: magnesium potassium silicon fluoride hydroxide oxide, and referenced as CAS number 273730-58-8
Trade name: MICROMICA
Composition formula: K₀.₇Mg₂.₇Si₄O₁₀F₂
Molecular weight: 403.33 g/mol
Purity of test item: ≥95%
Impurity: <5% water
Lot number: 776A
Key result
Water solubility:
ca. 1.02 mg/L
Conc. based on:
element (dissolved fraction)
Remarks:
total silcon content
Loading of aqueous phase:
1 g/L
Incubation duration:
>= 6 - <= 8 d
Temp.:
20 °C
pH:
ca. 6.6

Agitation period (days)

Sample

pH

Measured silicon content of the test solution (mg/L)

Concentration of test item in test solution* (mg/L)

Maximum measured difference (%)

 

Mean

4

1a

6.3

0.194

0.731

-

24.6

-

-

1b

6.3

0.195

0.732

5

2a

6.7

0.226

0.849

22.1

2b

6.5

0.225

0.845

6

3a

6.6

0.246

0.924

1.02

14.9

3b

6.6

0.258

0.970

7

4a

6.3

0.283

1.06

-

4b

6.3

0.289

1.09

8

5a

6.8

0.278

1.05

-

5b

6.9

0.281

1.05

*The silicon content of the test item was 26.6% so the measured silicon content of the test solution was multiplied by 3.76 (100/26.6) to calculate the concentration of test item in test solution.

As the maximum difference in silicon content between test solutions 3, 4 and 5 (a and b) was less than 15% (14.9%), it was judged that the silicon concentrations of these test solution reached equilibrium and are therefore valid. Samples 1 and 2 (a and b) are discounted.

Conclusions:
Aqueous samples, with a 1 g/L loading, were incubated for 6, 7 and 8 days at 30 °C and silicon content measured via ICP-AES. As the silicon content of the test item was 26.6%, the aqueous solubility of the test item was determined to be 1.02 mg/L at 20 °C.
Executive summary:

The aqueous solubility of the test item was measured in a GLP study performed using method OECD 105. Aqueous samples, with a 1 g/L loading, were incubated for 6, 7 and 8 days at 30 °C and silicon content measured via ICP-AES. As the silicon content of the test item was 26.6%, the aqueous solubility of the test item was determined to be 1.02 mg/L at 20 °C.

Data source

Materials and methods

Results and discussion

Applicant's summary and conclusion