Zirconium oxide, erbium and yttrium doped

Water solubility

Link to relevant study record(s)

Reference

Reference 1

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

Reason / purpose for cross-reference:

other: read-across target

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

Key result

Water solubility:

< 0.001 mg/L

Conc. based on:

element (dissolved fraction)

Remarks:

zirconium

Temp.:

20 °C

pH:

6.4

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.

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

Amount of test material 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 material 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).

Conclusions:

Under the conditions of the study, the test material is considered to be insoluble in water.

Executive summary:

The water solubility of the test material was investigated in a study which was conducted in accordance with the standardised methods OECD 105 and EU Method A.6, under GLP conditions, following 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.

Reference 2

Endpoint:

water solubility

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study conducted on read-across material

Justification for type of information:

Read-across to structurally similar substance erbium, gadolinium, yttrium and zirconium oxide (EC 946-001-8). The only difference between the substance being registered and the read-across substance is that the substance to be registered is missing the gadolinium oxide content (about 1.4%). The absence of this compound at such a low % is considered highly unlikely to affect its properties.

Reason / purpose for cross-reference:

read-across source

Water solubility:

< 0.001 mg/L

Conc. based on:

element (dissolved fraction)

Remarks:

zirconium

Temp.:

20 °C

pH:

6.4

Water solubility:

< 0.001 mg/L

Conc. based on:

element (dissolved fraction)

Remarks:

erbium

Temp.:

20 °C

pH:

6.4

Description of key information

Read-across to structurally similar substance erbium, gadolinium, yttrium and zirconium oxide (EC 946-001-8)

Under the conditions of the study, erbium gadolinium yttrium zirconium oxide is considered to be insoluble in water.

Additional information

The water solubility of the test material was investigated in a study which was conducted in accordance with the standardised methods OECD 105 and EU Method A.6, under GLP conditions, following the column elution method. The study was conducted on the read-across substance

erbium, gadolinium, yttrium and zirconium oxide (EC 946-001-8). The only difference between the substance being registered and the read-across substance is that the substance to be registered is missing the gadolinium oxide content (about 1.4%). The absence of this compound at such a low % is considered highly unlikely to affect its properties.

During the study, 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.