Aluminum magnesium oxide

Adsorption / desorption

Administrative data

Endpoint:

adsorption / desorption: screening

Type of information:

other: expert statement

Adequacy of study:

key study

Study period:

January 2019

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

26 July 2018 - 21 August 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Version / remarks:

2016

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

1995

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 830.7840 (Water Solubility)

Version / remarks:

1998

Deviations:

no

GLP compliance:

yes

Type of method:

column elution method

Key result

Water solubility:

0.013 mg/L

Conc. based on:

test mat. (dissolved fraction)

Remarks:

based on Al analysis

Temp.:

20 °C

pH:

>= 7.4 - <= 7.5

Details on results:

Mean concentration in the water samples (n=10) obtained at the flowrate of 24 mL/h was 0.014 mg/L. CV = 8.3%.
Mean concentration in the water samples (n=10) obtained at the flowrate of 12 mL/h was 0.011 mg/L. CV = 6.8%.
The maximum difference on the mean values at both flow rates was ≤ 30% (i.e. 25%). Average of two flow rates: 0.013 mg/L.

The coefficient of variation (CV) (n=10) was ≤ 30% at both flow rates. It demonstrated that the system was in equilibrium at all flow rates.

The turbidity of the eluates was < 0.2 NTU. According to this, no undissolved particles were detected in the eluates.

No test item was detected in the samples from the blank column.

Conclusions:

The water solubility of the substance at 20°C was determined to be approximately 0.013 mg/L.

Executive summary:

The water solubility of the substance was determined using the column elution method in a GLP study according to EC A.6, OECD 105 and OPPTS 830.7840.

Quantification was performed by ICP-MS (based on Al). The water solubility of the substance at 20°C was determined to be approximately 0.013 mg/L (average of two flow rates - 24 mL/h and 12 mL/h, measured value is < LOQ of the method and obtained through extrapolation of the calibration curve).

The coefficient of variation (CV) (n=10) was ≤ 30% at both flow rates.

The maximum difference on the mean values at both flow rates was ≤ 30%.

The pH of the aqueous samples was 7.4 -7.5.

Data source

Reference

Reference Type:

other: Expert statement

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

The suitability/applicability of available test guidelines for adsorption/desorption was theoretically assessed in relation to the inorganic nature of the substance.

GLP compliance:

no

Type of method:

other: theoretical assessment of the suitability/applicability of available test guidelines (HPLC, QSAR and batch equilibrium)

Test material

Test material information

Constituent 1

Reference substance name:

Aluminum magnesium oxide

EC Number:

234-386-9

EC Name:

Aluminum magnesium oxide

Cas Number:

11137-98-7

Molecular formula:

Al2MgxO(3+x) where x = 4.3-4.6

IUPAC Name:

Aluminum magnesium oxide

Test material form:

solid: particulate/powder

Details on test material:

- Appearance: White powder
- Storage condition: At room temperature desiccated

Results and discussion

Adsorption coefficient

Adsorption coefficient 1

Key result

Type:

log Koc

Remarks on result:

not determinable

Remarks:

- HPLC screening method not applicable for inorganic substances

Adsorption coefficient 2

Key result

Type:

log Koc

Remarks on result:

not determinable

Remarks:

- QSAR (based on log Pow) not applicable due to lack of Pow data (not possible/meaningful to determine for inorganic substances)

Any other information on results incl. tables

Column 2 of the REACH Annex VIII endpoint point 9.3.1. (Adsorption/desorption screening) provides 2 specific adaptation rules from the standard information requirements.

However, these adaptation rules cannot be applied to inorganic substances for the following reasons:

- the potential for adsorption based on e.g. a low octanol water partition coefficient cannot be assessed for inorganic substances because the octanol water partition coefficient of inorganic substances can usually not be determined (e.g. due to solubility issues).

- rapid decomposition of degradation products is not applicable because inorganic substances do not degrade in a similar fashion as organic substances.

Proposed screening methods, such as the HPLC estimation method or QSAR, are not deemed applicable due to the inorganic nature of the substance, its poor solubility in water and commonly used solvents in the HPLC screening test as well as expected detection issues. In addition, the HPLC estimation method is not validated for inorganic substances, as pointed out in the test guidelines (OECD 121 and EU C.19). Furthermore, no valid QSAR models are available for inorganic substances to predict physico-chemical properties, so it is not possible to provide e.g. a calculated log Pow value (nor details of the calculation method, or details on the applicability domain of the model), and thus calculation of log Koc (based on log Pow) is also not possible.

Finally, the applicability of performing a batch equilibrium method was assessed. Considering that, due to the inorganic nature of the substance in combination with its poor solubility in water, most of the parameters required as a pre-requisite for performing an OECD 106 test (abiotic degradation, log Pow, ready biodegradability, pKa and direct photolysis in water) cannot be acquired, and taking into account that analytical monitoring of the substance as such (or dissolved ions) in test solutions at very low concentrations is not expected to be accurate and reliable, due to sensitivity issues, it was concluded that a batch equilibrium test very likely cannot be performed either.

Applicant's summary and conclusion

Validity criteria fulfilled:

not applicable

Conclusions:

Based on available physico-chemical information and in view of the inorganic nature of the substance it is concluded that it is considered scientifically justified to waive testing for adsorption/desorption of this inorganic substance.