reaction mass of cerium(IV)oxide, praseodymium(III,IV)oxide and zirconium (IV)oxide

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

31 October 2017 - 15 March 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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:

< 0.02 mg/L

Conc. based on:

element (dissolved fraction)

Remarks:

zirconium

Temp.:

20 °C

pH:

6

Remarks on result:

other: Expressed as zirconium content in water; mean of flow rates 25 mL/h and 12.5 mL/h.

Key result

Water solubility:

< 0.02 mg/L

Conc. based on:

element (dissolved fraction)

Remarks:

cerium

Temp.:

20 °C

pH:

6

Remarks on result:

other: Expressed as cerium content in water; mean of flow rates 25 mL/h and 12.5 mL/h.

Details on results:

Zirconium:
Results were validated by:
- Linearity validation: The analysis showed a good linearity of the method (r > 0.99).
- Accuracy validation: Results in dilution mixture showed a good accuracy which indicates acceptable data (recoveries ranged between 70 and 110%).
- Repeatability validation: The results indicated a good precision of the data (RSD < 20%).
- Specificity: The intensity (CPS) of blank samples measured was negligible.
- Limit of quantification: 0.02 mg Zr/L
- Limit of detection: 0.01 mg Zr/L

Cerium:
Results were validated by:
- Linearity validation: The analysis showed a good linearity of the method (r > 0.99).
- Accuracy validation: Results in dilution mixture showed a good accuracy which indicates acceptable data (recoveries ranged between 70 and 110%).
- Repeatability validation: The results indicated a good precision of the data (RSD < 20%).
- Specificity: The intensity (CPS) of blank samples measured was negligible.
- Limit of quantification: 0.02 mg Ce/L
- Limit of detection: 0.01 mg Ce/L

Results of the preliminary test with milliQ water at pH 6 were:

Amount of test item weighed (g)	0.1	0.1	0.1	0.1	0.1	0.1	0.01
Volume of water added (mL)	0.1	0.5	1	2	10	100	1000
Solubility (yes/no)	No	No	No	No	No	No	No (after > 96 h of agitation of the test solution)

Results of the preliminary test with milliQ water at pH 4 were:

Amount of test item weighed (g)	0.1	0.1	0.1	0.1	0.1	0.1	0.01
Volume of water added (mL)	0.1	0.5	1	2	10	100	1000
Solubility (yes/no)	No	No	No	No	No	No	No (after > 96 h of agitation of the test solution)

Results of the preliminary test with milliQ water at pH 7 were:

Amount of test item weighed (g)	0.1	0.1	0.1	0.1	0.1	0.1	0.01
Volume of water added (mL)	0.1	0.5	1	2	10	100	1000
Solubility (yes/no)	No	No	No	No	No	No	No (after > 96 h of agitation of the test solution)

Results of the preliminary test with milliQ water at pH 9 were:

Amount of test item weighed (g)	0.1	0.1	0.1	0.1	0.1	0.1	0.01
Volume of water added (mL)	0.1	0.5	1	2	10	100	1000
Solubility (yes/no)	No	No	No	No	No	No	No (after > 96 h of agitation of the test solution)

Results of the main test:

	Solubility expressed as Zirconium content in water (mg/L)	Solubility expressed as Cerium content in water (mg/L)	Mean pH measured	Temperature (°C)
Test 1 (flow 25 mL/h)	< 0.02	< 0.02	6	20
Test 2 (flow 25 mL/h)	< 0.02	< 0.02	6	20
Mean (Test 1 and Test 2)	< 0.02	< 0.02	6	20
Test 3 (flow 12.5 mL/h)	< 0.02	< 0.02	6	20
Mean (12.5 mL/h and 25 mL/h)	< 0.02	< 0.02	6	20

Conclusions:

During the water solubility test with the reaction mass of cerium dioxide, praseodymium oxide and zirconium dioxide, performed according to the column elution method, the water solubility of zirconium and cerium from the test substance was determined to be < 0.02 mg/L for both elements, indicating that the material is highly insoluble. The test was performed at 20°C and the average pH measured during the test was 6.

Description of key information

In the GLP-compliant guideline study (Buchholz, 2018; Klimisch 1) within which the solubility in water of one batch of the reaction mass of cerium dioxide, praseodymium oxide and zirconium dioxide was determined according to the EU A.6 method and OECD guideline 105, the mean solubility in water was determined to be < 0.02 mg/L at pH 6 and 20°C for both zirconium and cerium, according to the column elution method. The material can therefore be concluded to be highly insoluble.