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Water solubility

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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

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

Additional information