Manganese alumina pink corundum

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-08-03 to 2010-03-10

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

deviations from the guideline, which do not effect the validity of the study: (a) `mass balance (%) after completion of the transformation test´ is missing (b) the between-vessel variation was not always below the demanded limit (<20 %).

Qualifier:

according to guideline

Guideline:

OECD Series on Testing and Assessment No. 29 (23-Jul-2001): Guidance document on transformation/dissolution of metals and metal compounds in aqueous media

Deviations:

yes

Remarks:

please refer to the field "Rationale for reliability incl. deficiencies" above

GLP compliance:

yes

Type of method:

other: transformation/dissolution

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

3.781 µg/L

Element analysed:

Al

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

pH 8

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

3.261 µg/L

Element analysed:

Al

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

pH 6

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

6.41 µg/L

Element analysed:

Mn

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

pH 8

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

121.221 µg/L

Element analysed:

Mn

Loading of aqueous phase:

100 mg/L

Incubation duration:

24 h

Test conditions:

pH 6

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

1.482 µg/L

Element analysed:

Mn

Loading of aqueous phase:

100 mg/L

Incubation duration:

7 d

Test conditions:

pH 6.15, Temp.: 20.7 °C, O2: 8.1 mg/L

Remarks on result:

other: SD: ± 1.6780 µg/L

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

< 0.01 µg/L

Element analysed:

Al

Loading of aqueous phase:

100 mg/L

Incubation duration:

7 d

Test conditions:

pH: 6.15, Temp.: 20.7 °C, O2: 8.1 mg/L

Remarks on result:

other: < LOD

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

4.033 µg/L

Element analysed:

Mn

Loading of aqueous phase:

1 mg/L

Incubation duration:

24 h

Test conditions:

pH: 6.17, Temp.: 20.0 °C, O2: 10.0 mg/L

Remarks on result:

other: SD: ± 0.9813 µg/L

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

0.133 µg/L

Element analysed:

Al

Loading of aqueous phase:

1 mg/L

Incubation duration:

24 h

Test conditions:

pH: 6.17, Temp.: 20.0 °C, O2: 10.0 mg/L

Remarks on result:

other: SD: ± 0.0102 µg/L

Key result

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

10.66 µg/L

Element analysed:

Mn

Loading of aqueous phase:

1 mg/L

Incubation duration:

7 d

Test conditions:

pH: 6.1, Temp.: 21.1 °C, O2: 8.4 mg/L

Remarks on result:

other: SD: 1.3894 µg/L

Key result

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

0.29 µg/L

Element analysed:

Al

Loading of aqueous phase:

1 mg/L

Incubation duration:

7 d

Test conditions:

pH: 6.1, Temp: 21.1 °C, O2: 8.4 mg/L

Remarks on result:

other: SD: ± 0.0172 µg/L

Key result

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

8.911 µg/L

Element analysed:

Mn

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

pH: 6.19, Temp: 21.5 °C, O2: 6.4 mg/L

Remarks on result:

other: SD: ± 3.1129 µg/L

Key result

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

0.042 µg/L

Element analysed:

Al

Loading of aqueous phase:

1 mg/L

Incubation duration:

28 d

Test conditions:

pH: 6.19, Temp.: 21.5 °C, O2: 6.4 mg/L

Remarks on result:

other: SD: ± 0.0588 µg/L

Details on results:

Aluminum ions dissolved/transformed in aqueous solutions. The maximum solubility was observed after 2 hours for the 100 mg/L loading in the 7-d test. Dissolved concentrations were lower at day 7 indicating a possible reprecipitation of the metal salts. The maximum solubility was observed after 7-days for the 1 mg/L loading in the 28-d test. Dissolved concentrations were lower at day 10, 16 and 28 indicating also a possible re-precipitation of the metal salts.
Manganese ions dissolved/transformed in aqueous solutions. The maximum solubility was observed after 24 hours for the 100 mg/L loading in the 7-d test.
Dissolved concentrations were lower at day 7 indicating a possible reprecipitation of the metal salts. The maximum solubility was observed after 16-days for the 1 mg/L loading in the 28-d test. Dissolved concentrations were lower at day 28 indicating also a possible re-precipitation of the metal salts.

Test conditions are closely in accordance with guideline:

- Vessel Variation:

The within-vessel variations from the 100 mg/L loadings were between 0.002 and 0.5263 % (i.e.≤10 %).

The between-vessel variation was 113.1872 % (Mn) (i.e.> 20 %- not guideline comform) and 0 % (Al) (i.e.≤ 20 %) at the 7- day endpoint.

UN/SCEGHS/3/INF.5/Add.9 guideline requires for a standard set-up of three replicate test vessels and two replicate samples per test vessel at each sampling time, it is reasonable to anticipate that for a constant loading of a substance, tested in a narrow particle size (e.g. 37 - 44 μm) and total surface area range, the within-vessel variation in transformation data should be less than 10 % and the between-vessel variation should be less than 20 %. If we consider the final average the VC between vessels is slightly higher than 20 %, as requested by the guideline UN/SCEGHS/3/INF.5/Add.9, even taking into account the precision of the analytical method estimated at 6.01 % for Aluminum and 7.11 % for Manganese, the results are slightly high, but we consider them acceptable.

The within-vessel variations from the 1mg/L loading were between 0.2563 and 3.3496% (i.e.≤ 10 %).

The between-vessel variation was 13.0366 % (Mn) (i.e.≤ 20 %) and 5.9392 % (Al) (i.e.≤ 20%) at the 7-day endpoint.

- The air oxgen concentrations were in the range of 6.0 mg/L and 10.2 mg/L and all above the acceptable limit (>70 % of air O₂ concentration = 6.02 mg/L).

- The temperature was in the range from 19.7 °C to 22.3 °C (i.e. not between 20 - 25 °C +/-2 °C). There was only one data out of the acceptable range (at 16 days with the 1 mg/L loading) all the other data and all the average data of the samples were inside of the acceptable range.

- The pH was in the range of 6.0 to 6.2 (i.e. in the range of pH 6 + 0.2 units)

Conclusions:

The transformation/dissolution of MANGANESE ALUMINA PINK CORUNDUM was measured according to the method OECD test series no. 29 (Guidance document on transformation/dissolution of metals and metal compounds in aqueous media). The transformation/dissolution of MANGANESE ALUMINA PINK CORUNDUM at pH 6, the pH that maximises dissolution, resulted in the following dissolved concentrations:

1 mg/L, 7 days: 10.66 ± 1.39 µg Mn/L, 0.29 ± 0.02 µg Al/L
1 mg/L, 28 days: 8.91 ± 3.11 µg Mn/L, 0.042 ± 0.06 µg Al/L
100 mg/L, 7 days: 1.48 ± 1.68 µg Mn/L, <0.01 (
As dissolved Mn and Al concentrations were below 11 µg/L even at the highest loading of 100 mg/L, referring to a solubility of < 0.011 %, manganese alumina pink corundum is considered environmentally inert.

Description of key information

The solubility of manganese alumina pink corundum in environmental media is low. In a GLP-conform transformation/dissolution screening test with a loading of 100 mg/L, a higher Mn release was observed at pH 6, whereas the release of Al was comparable at both pH.

In a short-term transformation/dissolution test with a loading of 100 mg/L at pH6, a dissolved Al concentration below LOD (0.01 microg/L) was determined whereas the dissolved Mn concentration was 1.48 microg/L after 7 days (Grane, 2010). Transformation/dissolution at a loading of 1 mg/L at pH 6 resulted in dissolved Mn concentrations of 10.66 microg/L after 7 and 8.91 microg/L after 28 days. The dissolved Al concentrations at pH 6 were 0.29 microg/L and 0.042 microg/L after 7 and 28 days, respectively (Grane, 2010). The particle size of the tested sample (BET surface area 2.51 m2/g) is representative for the particle size marketed. Thus, the extent to which "Manganese alumina pink corundum " can produce soluble available ionic and other metal-bearing species in aqueous media is limited.

Additional information

The transformation/dissolution of Manganese alumina pink corundum was measured according to the method OECD test series no. 29 (Guidance document on transformation/dissolution of metals and metal compounds in aqueous media). The transformation/dissolution of Manganese alumina pink corundum at pH 6, the pH that maximises dissolution, resulted in the following dissolved concentrations:

 

1 mg/L, 7 days: 10.66 ± 1.39 µg Mn/L, 0.29 ± 0.02 µg Al/L      

1 mg/L, 28 days: 8.91 ± 3.11 µg Mn/L, 0.042 ± 0.06 µg Al/L

100 mg/L, 7 days: 1.48 ± 1.68 µg Mn/L, <0.01 (<LOD)      

 

As dissolved Mn and Al concentrations were below 11 µg/L even at the highest loading of 100 mg/L, referring to a solubility of < 0.011 %, manganese alumina pink corundum is considered environmentally inert.