2-ethylhexanoic acid, cerium salt

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018-08-10 to 2018-08-16

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Version / remarks:

1995

Deviations:

yes

Remarks:

Three vessels were set up in a parallel design, each vessel was sampled several times instead of sampling one vessel at every point in time/ exclusion of O2 and CO2, under inert gas (argon)

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Version / remarks:

2008

Deviations:

yes

Remarks:

Three vessels were set up in a parallel design, each vessel was sampled several times instead of sampling one vessel at every point in time/ exclusion of O2 and CO2, under inert gas (argon)

GLP compliance:

no

Type of method:

flask method

Key result

Water solubility:

938 mg/L

Conc. based on:

test mat. (dissolved fraction)

Loading of aqueous phase:

1 g/L

Incubation duration:

>= 1 - <= 3 d

Temp.:

20 °C

pH:

>= 5.37 - <= 5.8

Remarks on result:

other: S.D.: ± 51 mg test item/L

Remarks:

Calculated on a mean of dissolved cerium concentration of 216 ± 12 mg/L and a cerium content of 23.0 %.

Water solubility:

216 mg/L

Conc. based on:

element (dissolved fraction)

Remarks:

Ce

Loading of aqueous phase:

1 g/L

Incubation duration:

>= 1 - <= 3 d

Temp.:

20 °C

pH:

>= 5.37 - <= 5.8

Remarks on result:

other: S.D.: ± 12 mg Ce/L

Details on results:

- Mean temperature: 20.1 ± 0.2 °C
- pH values: solutions containing the test item: 5.4 – 5.8, method blanks: 7.2 - 8.5.
- Oxygen concentration: No oxygen was measurable
- Turbidity: The turbidity in samples from test was always 0.02 NTU indicating that filtered solutions did not contain any undissolved material immediately after filtering.

Analytical measurements
The calculated variations / changes between sampling points were less than 15 % for the day 1, 2 and 3. Thus, the validity criteria as foreseen in OECD 105 and Regulation 440/2008/EC A.6 were fulfilled. Based on the dissolved measured cerium concentration the content of dissolved test item is calculated. Cerium concentrations in method blanks were measured to be below the LOD (LOD = 0.003 μg/L Ce).

ICP-MS measurement series with corresponding LOD/LOQ, correlation coefficient and sum of quality assurance samples and recovery

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 [%]
August 16, 2018; measurement of test samples and method blanks (day 1, 2, 3)
1.0 – 500 (total of 11 calibration points, 11 used + blank)	^142Ce in helium mode	Ce: 0.003	Ce: 0.008	Ce: 0.9999	Ce: 21	Ce: 100

Recovery/ validation data of cerium - measurement series on August 16, 2018

Element Ce	Recovery [%]	SD [%]	n (total)	n (valid)
Roth + Ce 40 μg/L	94.4	1.7	6	6
Roth + Ce 400 μg/L	101	1.6	6	6
Recalibration standard 100 μg/L	94.1	1.3	6	6

Fortification of measurement series on August 16, 2018

Sample	element	measured concentration [μg/L]	calculated level after addition [μg/L]	recovery [μg/L] / [%]
Vessel 2 sample b 1d (18AB1451, dilution 2000-fold) – 1 mL sample, 4 mL 200 μg/L standard	Ce	113	183	184 / 101
Vessel 1 sample b 2d (18AB1465, dilution 2000-fold) – 1 mL sample, 4 mL 300 μg/L standard	Ce	107	261	259 / 99.2
Vessel 2 sample b 3d (18AB1463 dilution 2000-fold) – 1 mL sample, 4 mL 400 μg/L standard	Ce	105	341	336 / 98.5

Measured dissolved Ce concentrations of solutions containing the test item (1d, 2d, 3d: triplicate vessels; a, b: duplicate samples).

Sample	LOD [µg/L]	LOQ [µg/L]	Measured Ce conc. [µg/L]	Ce conc. [mg/L] (dilution factor: 2000)	Mean Ce conc. per vessel ± SD [mg/L]	Mean Ce conc. all vessels ± SD [mg/L]	Variation / change between samplings [%]
1a day 1	0.003	0.008	113	225	228 ± 4	223 ± 5
1b day 1			116	231
2a day 1			106	213	219 ± 9
2b day 1			113	226
3a day 1			110	220	221 ± 1
3b day 1			111	222
1a day 2	0.003	0.008	102	204	209 ± 7	214 ± 12	3.9
1b day 2			107	214
2a day 2			108	216	228 ± 7
2b day 2			120	240
3a day 2			112	224	206 ± 25
3b day 2			94.2	189
1a day 3	0.003	0.008	105	210	212 ± 3	210 ± 3	2.2
1b day 3			107	215
2a day 3			101	201	206 ± 7
2b day 3			105	210
3a day 3			104	207	211 ± 5
3b day 3			107	215

 Calculation of water solubility according to ceriumin test item

Sample	Ce conc. [mg/L]	Mean Ce conc. [mg/L]	SD [mg/L]	Mean Ce all samples [mg/L]	SD [mg/L]	Ce in test item [%]	Calculated amount of test item dissolved on basis of Ce (100% Purity) [mg/L]	Mean dissolved test item [mg/L]	SD [mg/L]	Mean all samples [mg/L]	SD [mg/L]
1a day 1	225	217	010	216	12	23.0	980	942	043	938	51
1b day 1	231						1005
1a day 2	204						887
1b day 2	214						931
1a day 3	210						914
1b day 3	215						933
2a day 1	213	218	13				925	947	59
2b day 1	226						983
2a day 2	216						940
2b day 2	240						1042
2a day 3	201						875
2b day 3	210						915
3a day 1	220	213	13				958	925	58
3b day 1	222						967
3a day 2	224						973
3b day 2	189						820
3a day 3	207						901
3b day 3	215						934

Conclusions:

Under the conditions of this test (under exclusion of CO2 and O2, under inert gas; flask method; loadings of ~ 4 g/L test substance for three replicates), a solubility equilibrium was reached. The mean of dissolved cerium concentrations (< 0.22 μm) measured on day 1, 2 and 3 at 20.1 ± 0.3 °C is 216 ± 12 mg/L via ICP-MS, corresponding to a water solubility of 938 ± 51 mg /L test item, based on a cerium content of 23.0 %.

Description of key information

Under the conditions of this test (under exclusion of CO2 and O2, under inert gas; flask method; loadings of ~ 4 g/L test substance for three replicates), a solubility equilibrium was reached. The mean of dissolved cerium concentrations (< 0.22 μm) measured on day 1, 2 and 3 at 20.1 ± 0.3 °C is 216 ± 12 mg/L via ICP-MS, corresponding to a water solubility of 938 ± 51 mg /L test item, based on a cerium content of 23.0 %.

Key value for chemical safety assessment

Water solubility:

938 mg/L

at the temperature of:

20 °C