Cerium(3+) neodecanoate

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2019-01-08 to 2019-03-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

deviations do net effect the integrity of the study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

1995

Deviations:

yes

Remarks:

3 vessels (test item), 2 method blanks were set up in a parallel design, each vessel was sampled several times/ Test under argon, exclusion of O2 and CO2 / Homogenisation of the test item (2nd test)/ Max. temp. was not always 20.0±1.0°C (21.3°C, 2nd test)

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2015-12-16

Type of method:

flask method

Specific details on test material used for the study:

- Storage condition of test material: Room temperature, closed
- Treatment of test material prior to second testing:
It was decided to homogenise the test item by heating up slowly to 85 °C in a water bath and carefully stirring manually with a PTFE spatula. As the test item became more fluid heating up to 85 °C was considered to be sufficient for sampling. Sample aliquots were weighed into test vessels (3 replicates) and a second main test was started. This is not critical and has no influence on the validity and quality of the study because heating up the test item to 85 °C allows to take a sample that is representative for the test item. Hence, test results should be more precise.

Water solubility:

29.9 µg/L

Conc. based on:

element (dissolved fraction)

Remarks:

Cerium

Loading of aqueous phase:

50 other: mg test item / L

Incubation duration:

>= 1 - <= 17 d

Temp.:

20 °C

pH:

>= 6.1 - <= 7

Remarks on result:

other: S.D.: ± 14.1 μg Ce/L

Key result

Water solubility:

157.5 µg/L

Conc. based on:

test mat. (dissolved fraction)

Loading of aqueous phase:

50 mg/L

Incubation duration:

>= 1 - <= 17 d

Temp.:

20 °C

pH:

>= 6.1 - <= 7

Remarks on result:

other: S.D.: ± 74.4 μg/L

Remarks:

water solubility of the test item was calculated based on a cerium content of 19 % and a dissolved cerium amount of 29.9 ± 14.1 μg/L.

Details on results:

Temperature:
- The mean temperature in the preliminary test was 20.2 ± 0.1 °C. The recorded minimum temperature was 20.1 °C and the maximum was 20.8 °C.
- The mean temperatures in the 1st main test after test start were 20.3 ± 0.1 °C and 20.1 ± 0.1 °C. The minimum temperature was 19.8 °C and the maximum was 21.0 °C.
- The mean temperatures in the 2nd main test after test start were 20.1 ± 0.2 °C and 19.8 ± 0.2 °C. The minimum temperature was 19.7 °C and the maximum was 21.3 °C.

Measured solution pH:
- In the 1st test the pH of solutions containing the test item were in the range of 5.4 – 6.6, whereas the pH of method blanks were in the range of 5.7 - 7.6.
- In the 2nd test the pH of solutions containing the test item were in the range of 6.1 – 7.0, whereas the pH of method blanks were in the range of 6.1 - 7.3.

Oxygen concentration:
- The oxygen concentration was measured throughout the preliminary test, pre saturation phases and during the main tests at 20.0 ± 1.0 °C. The measured O2 concentrations were always below 1.6 % and around 0 %.

Turbidity:
- The turbidity in samples from main tests was always < 1 NTU indicating that filtered solutions did not contain any undissolved material immediately after filtering.

ICP-OES measurement series (on January 25, 2019) - preliminary test.

Calibration [µg/L] – lowest and highest calibration point	Chosen wavelength [nm]	LOD [µg/L]	LOQ [µg/L]	Correlation coefficient	Sum of quality assurance samples	Recovery of quality assurance samples [%]
1.0 – 1000 (total of 13 calibration points, 12 used + blank)	456.236	Ce: 1.45	Ce: 4.34	Ce: 1.000	Ce: 9	Ce: 100

 

Recovery/validation data cerium of measurement series on January 25, 2019 (preliminary test)

Element Ce	Recovery [%]	SD [%]	n (total)	n (valid)
Recalibration 25 µg/L	107	1	2	2
LabKings + Ce 50 µg/L	102	1	2	2
Recalibration 250 µg/L	101	<1	2	2
LabKings + Ce 500 µg/L	100	1	2	2

 

Fortification of measurement series on January 25, 2019 (preliminary test)

Sample	Element	Measured concentration [µg/L]	Calculated level after addition [µg/L]	Recovery [µg/L] / [%]
19Y0085: Sample a from test vessel in preliminary test, (dilution 10-fold) – 1 mL sample and 4 mL 250 µg/L standard	Ce	117	223	223 / 99.7 #

# Internal calculations were performed with more digits.

ICP-MS measurement series

Calibration [µg/L] – lowest and highest calibration point	Chosen isotope	LOD [µg/L]	LOQ [µg/L]	Correlation coefficient	Sum of quality assurance samples	Recovery of quality assurance samples [%]
January 25, 2019; measurement of test samples and method blanks from 1st test (days 1, 2, 3)
1.0 – 100 (total of 11 calibration points, 11 used + blank)	^140Ce in high helium mode	Ce: 0.0021	Ce: 0.0064	Ce: 0.9998	Ce: 19	Ce: 100
March 08, 2019; measurement of test samples and method blanks from 2nd test (days 1, 2, 3)
0.100 – 250 (total of 14 calibration points, 14 used + blank)	^142Ce in high helium mode	Ce: 0.0020	Ce: 0.0061	Ce: 1.000	Ce: 33	Ce: 100
March 22, 2019; measurement of test samples and method blanks from 2nd test (days 15, 16, 17)
0.250 – 500 (total of 14 calibration points, 14 used + blank)	^14ßCe in helium mode	Ce: 0.0003	Ce: 0.0009	Ce: 1.000	Ce: 33	Ce: 97.0

 

Recovery/validation data cerium of measurement series

Element Ce	Recovery [%]	SD [%]	n (total)	n (valid)
January 25, 2019 (1st test)
Recalibration 2 µg/L	99.1	0.3	4	4
LabKings + Ce 7.5 µg/L	98.7	0.4	4	4
Recalibration 20 µg/L	98.2	0.8	4	4
LabKings + Ce 75 µg/L	100	<1	4	4
March 08, 2019 (2nd test)
LabKings + Ce 0.75 µg/L	94.7	1.9	6	6
Recalibration 10 µg/L	104	2	6	6
LabKings + Ce 7.5 µg/L	94.0	0.6	6	6
Recalibration 100 µg/L	104	1	6	6
LabKings + Ce 75 µg/L	96.6	1.5	6	6
March 22, 2019 (2nd test)
LabKings + Ce 2.5 µg/L	98.8	0.8	6	6
Recalibration 10 µg/L	100	1	6	6
LabKings + Ce 25 µg/L	106#	10#	6#	5#
Recalibration 100 µg/L	107	3	6	6
LabKings + Ce 250 µg/L	105	3	6	6

^{#      Recovery of one sample is 125 %. This is not critical because 97.0 % of all QA/QC samples are within the limits of 100 ± 15 %.}

Fortification of measurement series

Sample	Element	Measured concentration [µg/L]	Calculated level after addition [µg/L]	Recovery [µg/L] / [%]
January 25, 2019 (1st test)
19Y0181: Vessel 3 sample a 1d – 1 mL sample and 4 mL 60 µg/L standard	Ce	0.339	48.1	49.5 / 103
19Y0199: Vessel 4 sample a 2d – 1 mL sample and 4 mL 80 µg/L standard	Ce	37.6	71.5	72.7 / 102
19Y0217: Vessel 5 sample a 3d – 1 mL sample and 4 mL 40 µg/L standard	Ce	29.5	37.9	37.4 / 98.7
March 08, 2019 (2nd test)
19Y0671: Vessel 4 sample a 1d – 1 mL sample and 4 mL 25 µg/L standard	Ce	45.9	29.2	29.0 / 99.4
19Y0689: Vessel 5 sample a 2d – 1 mL sample and, 4 mL 50 µg/L standard	Ce	24.2	44.8	44.9 / 100
19Y0703: Vessel 4 sample a 3d – 1 mL sample and 4 mL 10 µg/L standard	Ce	57.7	19.5	19.4 / 99.1
March 22, 2019 (2nd test)
19Y0749: Vessel 4 sample a 15d – 1 mL sample and 4 mL 50 µg/L standard	Ce	35.3	47.1	50.6 / 107
19Y0763: Vessel 3 sample a 16d – 1 mL sample and, 4 mL 75 µg/L standard	Ce	16.6	63.3	67.6 / 107
19Y0783: Vessel 5 sample a 17d – 1 mL sample and 4 mL 100 µg/L standard	Ce	11.1	82.2	85.9 / 104

Preliminary test:

Cerium concentrations were measured by ICP-OES. The mean measured dissolved Ce concentration was 1.17 ± <0.01 mg/L corresponding to 6.16 ± 0.01 mg/L test item (calculated based on Ce content of 19 %). According to the guideline at least five times the amount needed for a solubility equilibrium (observed in preliminary test) has to be applied in the main test.

1st test

Cerium concentrations in the range of 0.074 – 47.4 μg Ce /L were measured. Since the cerium concentration of replicate solutions differed by more than two magnitudes, it was decided to terminate the 1st test after 3 days and to start a 2nd test.

2nd test

Background cerium levels of method blanks were below the respective LOD and/or LOQ during the test. Measured dissolved cerium concentrations remained with a mean of about 40 μg Ce/L relatively constant on day 1, 2 and 3. However, in order to exclude that the concentrations would increase with time, the test was extended for 2 weeks. Measured dissolved cerium concentrations on day 15, 16 and 17 with a mean of 20 μg Ce/L were significantly lower than concentrations measured on day 1, 2 and 3. Thus, a decrease of dissolved Ce concentrations was observed during the test which may be explained with a slow Ce precipitation or reprecipitation of the solubilized test material.

Thus, the mean of Ce concentrations measured on day 1, 2, 3 and 15, 16 and 17 was used to estimate the water solubility of cerium neodecanoate, representative for the 17-day test.

Since, “the concentrations measured in at least the two last vessels [i.e. the concentrations measured on the last two sampling days] do not differ by more than 15%” and concentrations measured on the last two sampling days do not increase, the validity criteria of OECD 105 and Regulation 440/2008/EC A.6 are fulfilled.

The estimated water solubility of the test substance is based on mean dissolved cerium concentrations of all sampling days (1, 2, 3, 15, 16, 17) as follows:

1. Replicate: 27.2 ± 9.1 μg Ce /L

2. Replicate: 42.8 ± 11.9 μg Ce /L

3. Replicate: 19.7 ± 10.4 μg Ce /L

Mean: 29.9 ± 14.1 μg Ce /L

Based on the properties of the test item (UVCB substance, 19% cerium content), the water solubility of the test substance is calculated as follows:

Mean of concentration x 100 % / 19 %:

1. Replicate: 143.3 ± 48.0 μg/L test item

2. Replicate: 225.5 ± 62.4 μg/L test item

3. Replicate: 103.9 ± 54.7 μg/L test item

Mean: 157.5 ± 74.4 μg/L test item

Conclusions:

Under the conditions of this test (under exclusion of CO2 and O2, under inert gas; flask method; loadings of 50.1, 51.4 and 51.5 mg/L test substance for three replicates, respectively), a solubility equilibrium was reached. The mean of dissolved cerium concentrations (< 0.22 μm) measured on day 1, 2, 3 and 15, 16 and 17 at 20.0 ± 1.0 °C amounts to 29.9 ± 14.1 μg/L corresponding to a water solubility of 157.5 ± 74.4 μg/L test item based on a cerium content of 19 %. The pH of solutions containing the test item remained in the range of 6.1 – 7.0 whereas the pH of method blanks ranged from 6.1 - 7.3 during the main test.

Description of key information

Cerium neodecanoate has a water solubility of 157.5 ± 74.4 μg/L at 20.0 ± 1.0 °C and pH 6.1 -7.0.

Key value for chemical safety assessment

Water solubility:

157.5 µg/L

at the temperature of:

20 °C

Additional information

Under the conditions of this test (under exclusion of CO2 and O2, under inert gas; flask method; loadings of 50.1, 51.4 and 51.5 mg/L test substance for three replicates, respectively), a solubility equilibrium was reached. The mean of dissolved cerium concentrations (< 0.22 μm) measured on day 1, 2, 3 and 15, 16 and 17 at 20.0 ± 1.0 °C amounts to 29.9 ± 14.1 μg/L corresponding to a water solubility of 157.5 ± 74.4 μg/L test item based on a cerium content of 19 %. The pH of solutions containing the test item remained in the range of 6.1 – 7.0 whereas the pH of method blanks ranged from 6.1 - 7.3 during the main test.