zirconium(IV) oxide, stabilised with erbium(III) oxide, gadolinium(III) oxide and yttrium(III) oxide

Water solubility

Administrative data

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 July 2016 - 27 September 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

no

Test guideline 2

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

Test material

Test material information

Constituent 1

Reference substance name:

zirconium(IV) oxide, stabilised with erbium(III) oxide, gadolinium(III) oxide and yttrium(III) oxide

EC Number:

946-001-8

Molecular formula:

(Er2O3)w (Gd2O3)x (Y2O3)y (ZrO2)z: w/w% Er2O3 >= 1 <= 8 w/w% Gd2O3 >= 1 <= 8 w/w% Y2O3 >= 1 <= 8 w/w% ZrO2 >= 76 <= 97

IUPAC Name:

zirconium(IV) oxide, stabilised with erbium(III) oxide, gadolinium(III) oxide and yttrium(III) oxide

Test material form:

solid: particulate/powder

Details on test material:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: PEGYZ-23
- Expiration date of the lot/batch: 31 March 2021
- Purity: 100%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Controlled room temperature (15-25 ºC, below 70% relative humidity), protected from light.

OTHER SPECIFICS
Description: pink powder (the colour was determined by visual inspection upon arrival at test facility)
Safety precautions: Routine safety precautions (lab coat, gloves, safety glasses, face mask) for unknown materials were applied to assure personal health and safety. Possibly irritative.

Results and discussion

Water solubility

Water solubility 1

Key result

Water solubility:

< 0.001 mg/L

Conc. based on:

element (dissolved fraction)

Remarks:

zirconium

Temp.:

20 °C

pH:

6.4

Water solubility 2

Key result

Water solubility:

< 0.001 mg/L

Conc. based on:

element (dissolved fraction)

Remarks:

erbium

Temp.:

20 °C

pH:

6.4

Details on results:

Results were validated by:
- Linearity validation: The analysis showed a good linearity of the method (r > 0.99).
- Accuracy validation: Results of accuracy in dilution mixture showed a good accuracy which indicates acceptable data (recoveries ranged between 75% and 125%).
- Repeatability validation: The results indicated a good precision of the data.
- Specificity: The intensity (CPS) of blank samples measured was negligible or similar to solvent intensity.
- Limit of quantification: The LOQ was set at 0.1 ng/mL for Er (0.001 mg/L in the sample) and 0.15 ng/mL for Zr (0.001 mg/L in the sample).
- Limit of detection: The LOD was found to be 0.025 ng/mL for Er and 0.050 ng/mL for Zr.

Any other information on results incl. tables

Results of the preliminary test with milliQ water at pH 6.4 are as follows:

Amount of test item weighed (g)	0.01
Volume of water added (mL)	1000
Solubility (yes/no)	no (after 120 h of agitation)

Based on the preliminary test, the solubility of the test item is < 0.01 g/L. Therefore the main test was performed using the column elution method.

Results of the main test, expressed as erbium:

	Solubility expressed as erbium content in water (mg/L)	Mean pH measured	Temperature (°C)
Test 1 (flow 25 mL/hour)	< LOQ	6.4	20°C
Test 2 (flow 25 mL/hour)	0.001	6.4	20°C
Test 3 (flow 12.5 mL/hour)	< LOQ	6.4	20°C
Mean	< LOQ (0.001 mg/L)	6.4	20°C

Results of the main test expressed as zirconium:

	Solubility expressed as zirconium content in water (mg/L)	Mean pH measured	Temperature (°C)
Test 1 (flow 25 mL/hour)	< LOQ	6.4	20°C
Test 2 (flow 25 mL/hour)	< LOQ	6.4	20°C
Test 3 (flow 12.5 mL/hour)	< LOQ	6.4	20°C
Mean	< LOQ (0.001 mg/L)	6.4	20°C

The mean solubility in water is below LOQ at pH 6.4 and at 20°C (expressed as zirconium content in water).

Applicant's summary and conclusion

Conclusions:

The water solubility of the test substance was determined according to the column elution method. Zirconium concentrations were measured because zirconium represents the most dominant element in the material. Of the other elements, only erbium concentrations were measured because based on relative presence in the material and water solubility of the oxide forms, this element could reasonably be expected to be released the most (if any) from erbium gadolinium yttrium zirconium oxide, when in water. Both zirconium concentrations and erbium concentrations were however below the LOQ (0.001 mg/L for both elements) in all samples analysed, at a pH of 6.4 and a temperature of 20°C. In conclusion, erbium gadolinium yttrium zirconium oxide is considered to be insoluble in water.