Dipraseodymium dizirconium heptaoxide

Water solubility

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

22 October 2007 - 6 May 2008

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

Water solubility:

1.27 mg/L

Conc. based on:

test mat. (dissolved fraction)

Remarks:

recalculated based on measured dissolved Pr concentrations

Temp.:

20 °C

pH:

>= 6.59 - <= 6.76

Water solubility:

1.035 mg/L

Conc. based on:

element (dissolved fraction)

Remarks:

dissolved Pr

Temp.:

20 °C

pH:

>= 6.59 - <= 6.76

Details on results:

The measured results differ by less than 30%. Therefore, the study is considered to be valid.

Table 1: Water solubility (Column Elution Method)

Experiment No.	Flow rate (mL/h)	Sample No.	Concentra- tion analysed * (mg Pr/L)	Water solubility calculated (mg Test material/L)	Water solubility calculated (mg Test material/L)	Water solubility calculated (mg Test material/L)	pH
1	31	1 2 3 4 5	1.04* 1.04* 1.04* 1.03* 1.03*	1.36 1.36 1.36 1.35 1.35	1.35 SD = ± 0.007	1.27 SD = ± 0.10	6.66 6.70 6.59 6.76 6.63
2	16	6 7 8 9 10 11	0.92* 0.91* 0.89* 0.89* 1.01* 0.83*	1.20 1.19 1.16 1.16 1.32 1.08	1.19 SD = ± 0.08		6.69 6.71 6.70 6.75 6.68 6.72

SD = Standard deviation

* Values measured by ICP / MS

Conclusions:

The water solubility of the test material at 20°C was determined to be 1.27 mg/L (standard deviation ± 0.10 mg/L) using the column elution method.

Reference 2

Endpoint:

water solubility

Type of information:

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

Adequacy of study:

weight of evidence

Justification for type of information:

Read across from studies performed with the individual constituents of the reaction mass, i.e. praseodymium(III,IV) oxide and zirconium dioxide. The read across justification document is attached to IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Remarks on result:

other: Based on data obtained for the individual constituents of the reaction mass, it can be concluded that the reaction mass of praseodymium(III,IV) oxide and zirconium dioxide is a substance of poor water solubility.

Remarks:

The water solubility of praseodymium(III,IV) oxide was determined to be 1.27 mg/L (equivalent to 1.035 mg Pr/L) whereas that of zirconium dioxide was determined to be < 55 µg/L (equivalent to < 41 µg Zr/L). Consequently, the reaction mass of praseodymium(III,IV) oxide and zirconium dioxide is not expected to give rise to dissolved praseodymium or zirconium concentrations higher than these respective concentrations measured in these studies.

Reference 3

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2008-02-25 to 2010-09-03

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)

Remarks:

certificate provided by Rheinlandpfalz

Type of method:

column elution method

Water solubility:

< 55 µg/L

Temp.:

20 °C

pH:

6.5

Details on results:

Limit of detection was calculated from the calibrated range to be 40.8 µg/L Zr, corresponding to 55 µg/L ZrO2. As none of the samples showed a signal at the voltage of the Zr-Alizarin-peak, concentration in the samples and therefore water solubility was considered to lie below LOD.
No observations arousing doubts concerning the accuracy of the results and the validity of the study were made.

Conclusions:

The water solubility of the test item was found to be < 55 µg/L at a temperature of 20 +/- 0.5 degrees C and a pH of 6.5.

Description of key information

No experimental information is available on the water solubility of dipraseodymium dizirconium heptaoxide.

However, based on a weight of evidence approach including data obtained for its individual constituents, the substance can be concluded to be poorly soluble in water at room temperature and circumneutral pH. The water solubility of praseodymium(III,IV) oxide was determined to be 1.27 mg/L (equivalent to 1.035 mg Pr/L) whereas that of zirconium dioxide was determined to be < 55 µg/L (equivalent to < 41 µg Zr/L).

Consequently, dipraseodymium dizirconium heptaoxide is not expected to give rise to dissolved praseodymium or zirconium concentrations higher than these respective concentrations measured in these studies.

Additional information

1. Information on praseodymium(III,IV) oxide

Based on a guideline study (Weissenfeld, 2008; Klimisch 1), the water solubility of praseodymium(III,IV) oxide at 20°C was determined to be 1.27 mg/L (equivalent to 1.035 mg Pr/L). The pH measured in the test samples ranged from 6.59 to 6.76.

2. Information on zirconium dioxide

Based on a guideline study (Paulus, 2010; Klimisch 1), the water solubility of zirconium dioxide was found to be < 55 µg/L at a temperature of 20 +/- 0.5°C and a pH of 6.5. When expressed as zirconium concentration the water solubility was < 41 µg Zr/L.

3. Conclusion on the substance dipraseodymium dizirconium heptaoxide

Based on the data obtained for its individual constituents, the substance dipraseodymium dizirconium heptaoxide can be concluded to be poorly soluble in water at room temperature and circumneutral pH.