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Physical & Chemical properties

Water solubility

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Reference
Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 105 (Water Solubility)
Deviations:
yes
Remarks:
see "Details on methods" for details.
GLP compliance:
yes (incl. certificate)
Type of method:
flask method
Remarks:
Limit test
Key result
Water solubility:
5.7 µg/L
Conc. based on:
other: Cadmium
Temp.:
20 °C
pH:
>= 7.2 - <= 7.5
Details on results:
Preliminary test
Precipitation was observed which was independent from sample weight, measurements showed fluctuations.
It was thought that the fluctuations could be caused by (maybe inhomogeneous) impurities. Therefore following confirmation with the sponsor it was decided that it makes more sense to carry out the main test with different loading rates at one temperature (20 ° C).

Main test
The results of the solubility of "Cadmium selenide" in water with different loading rates at 20 °C.
The temperatures of the water baths were between 19.9 and 20.0 °C.
The pH of the solutions was 7.2 to 7.5 at both loading rates.

The solubilities showed constancy (criteria for constancy is a change of concentration of < 15 % compared with the day before) from the first sampling day (after 21 days of stirring) and was stopped after 23 days of stirring.

For calculation of the results all results were taken. The following results were obtained at the different loading rates:
100 mg test item / L: Solubility = < 5.7 µg test item / L
1000 mg test item / L: Solubility = < 5.7 µg test item / L

The replicates per loading rate were comparable. All results are lower than the limit of quantification.

Water solubility with an initial loading rate of 100 mg test item / L

Equilibration time

Loading rate 100 mg test item / L: Concentration of dissolved µg Cd / L

1streplicate

2ndreplicate

3rdreplicate

Mean

Day 21

< 3.3

< 3.3

< 3.3

< 3.3

Day 22

< 3.3

< 3.3

< 3.3

< 3.3

Day 23

< 3.3

< 3.3

< 3.3

< 3.3

Overall mean

< 3.3

Overall standard deviation

***

 

Equilibration time

Loading rate 100 mg test item / L: Concentration in µg test item / L

1streplicate

2ndreplicate

3rdreplicate

Mean

Day 21

< 5.7

< 5.7

< 5.7

< 5.7

Day 22

< 5.7

< 5.7

< 5.7

< 5.7

Day 23

< 5.7

< 5.7

< 5.7

< 5.7

Overall mean

< 5.7

Overall standard deviation

***

 

Equilibration time

Loading rate 100 mg test item / L: pH

1streplicate

2ndreplicate

3rdreplicate

Mean

Day 21

7.26

7.29

7.42

7.32

Day 22

7.29

7.18

7.33

7.27

Day 23

7.38

7.22

7.41

7.34

Overall mean

7.31

Overall standard deviation

0.04

 


Water solubility with an initial loading rate of 1000 mg test item / L

Equilibration time

Loading rate 1000 mg test item / L: Concentration of dissolved µg Cd / L

1streplicate

2ndreplicate

3rdreplicate

Mean

Day 21

< 3.3

< 3.3

< 3.3

< 3.3

Day 22

< 3.3

< 3.3

< 3.3

< 3.3

Day 23

< 3.3

< 3.3

< 3.3

< 3.3

Overall mean

< 3.3

Overall standard deviation

***

 

Equilibration time

Loading rate 1000 mg test item / L: Concentration in µg test item / L*)

1streplicate

2ndreplicate

3rdreplicate

Mean

Day 21

< 5.7

< 5.7

< 5.7

< 5.7

Day 22

< 5.7

< 5.7

< 5.7

< 5.7

Day 23

< 5.7

< 5.7

< 5.7

< 5.7

Overall mean

< 5.7

Overall standard deviation

***

 

Equilibration time

Loading rate 1000 mg test item / L: pH

1streplicate

2ndreplicate

3rdreplicate

Mean

Day 21

7.38

7.24

7.40

7.34

Day 22

7.29

7.31

7.30

7.30

Day 23

7.36

7.38

7.51

7.42

Overall mean

7.35

Overall standard deviation

0.06

 

Analytical method:    

A method was validated to determine the content of cadmium in water to calculate the water solubility of the test item “Cadmium selenide”.

Linearity:

The calibration curve was linear from the quantification limit up to the highest concentration of 100 µg Cd / L.

Detection limit:

0.19 µg Cd / L

Quantification limit:

0.66 µg Cd / L

Residual standard deviation:

24 cps

Method standard deviation:

0.24 µg Cd / L

Relative method standard deviation:

0.62 %

Detection limit

0.19 µg Cd / L in the diluted samples, which corresponds to 1.7 µg test item / L calculated with a dilution factor of 5 (rounded up to two significant digits).

Quantification limit

0.66 µg Cd / L in the diluted samples, which corresponds to 5.7 µg test item / L calculated with a dilution factor of 5 (rounded up to two significant digits).

Residual standard deviation

The residual standard deviation was 24 counts per second (cps) in the diluted samples.

 

Detection limit

0.19 µg Cd / L in the diluted samples, which corresponds to 1.7 µg test item / L calculated with a dilution factor of 5 (rounded up to two significant digits).

Quantification limit

0.66 µg Cd / L in the diluted samples, which corresponds to 5.7 µg test item / L calculated with a dilution factor of 5 (rounded up to two significant digits).

Residual standard deviation

The residual standard deviation was 24 counts per second (cps) in the diluted samples.

Method standard deviation

The method standard deviation was 0.24 µg Cd / L in the diluted samples.

 

Relative method standard deviation

The relative method standard deviation was 0.62 %.

Accuracy

Sample

Measured concentration
without addition
(µg Cd / L)

Added concentration
calculated
(µg Cd / L)

Measured concentration
with addition
(µg Cd / L)

Added concentration
measured
(µg Cd / L)

Recovery (%)

Measurement 1

0*

10

10.110

10.110

101

Measurement 2

0*

10

10.270

10.270

103

Measurement 3

0*

10

10.380

10.380

104

 

 

 

 

Mean:

103

* As the measured concentration of the samples without addition was below the quantification limit, as value of 0 was used for the calculation of the recovery.

The mean recovery of the standard addition experiment was 103 %.


Specificity/ Selectivity

The specificity of the element cadmium was proved by using two different wavelengths which are characteristic and specific for cadmium. The specificity was calculated from the measurements of the spiked samples from the accuracy experiments.

Sample

Measured concentration
(µg Cd / L)

214.400 nm

228.802 nm

Measurement 1

10.110

10.400

Measurement 2

10.270

10.290

Measurement 3

10.380

10.420

Mean

10.253

10.370

The deviation between the two wavelengths was lower than 3 % relative and prove the specificity of the used wavelengths.

Repeatability/ Reproducibility

Sample

Intensity
[counts / s]

RSD

1

2

3

4

5

6

[%]

Level 1

634.658

638.337

640.563

644.510

643.214

638.246

0.6

Level 2

1124.435

1136.065

1127.236

1131.720

1124.749

1128.226

0.4

Level 3

2645.805

2661.940

2652.675

2663.526

2644.614

2645.773

0.3

Level 4

5056.573

5124.987

5116.134

5102.950

5095.017

5113.846

0.5

Level 5

7572.560

7608.715

7623.466

7611.561

7587.270

7576.395

0.3

Level 6

10120.095

10100.092

10023.629

10123.583

10144.631

10104.785

0.4

The relative standard deviations (RSD) lower than 5 % of the different levels prove the precision of the analysis.

The method standard deviation was 0.24 µg Cd / L in the diluted samples.

 

Relative method standard deviation

The relative method standard deviation was 0.62 %.

 

Accuracy

Sample

Measured concentration
without addition
(µg Cd / L)

Added concentration
calculated
(µg Cd / L)

Measured concentration
with addition
(µg Cd / L)

Added concentration
measured
(µg Cd / L)

Recovery (%)

Measurement 1

0*

10

10.110

10.110

101

Measurement 2

0*

10

10.270

10.270

103

Measurement 3

0*

10

10.380

10.380

104

 

 

 

 

Mean:

103

* As the measured concentration of the samples without addition was below the quantification limit, as value of 0 was used for the calculation of the recovery.

The mean recovery of the standard addition experiment was 103 %.


Specificity/ Selectivity

The specificity of the element cadmium was proved by using two different wavelengths which are characteristic and specific for cadmium. The specificity was calculated from the measurements of the spiked samples from the accuracy experiments.

 

Sample

Measured concentration
(µg Cd / L)

214.400 nm

228.802 nm

Measurement 1

10.110

10.400

Measurement 2

10.270

10.290

Measurement 3

10.380

10.420

Mean

10.253

10.370

The deviation between the two wavelengths was lower than 3 % relative and prove the specificity of the used wavelengths.

Repeatability/ Reproducibility

Sample

Intensity
[counts / s]

RSD

1

2

3

4

5

6

[%]

Level 1

634.658

638.337

640.563

644.510

643.214

638.246

0.6

Level 2

1124.435

1136.065

1127.236

1131.720

1124.749

1128.226

0.4

Level 3

2645.805

2661.940

2652.675

2663.526

2644.614

2645.773

0.3

Level 4

5056.573

5124.987

5116.134

5102.950

5095.017

5113.846

0.5

Level 5

7572.560

7608.715

7623.466

7611.561

7587.270

7576.395

0.3

Level 6

10120.095

10100.092

10023.629

10123.583

10144.631

10104.785

0.4

The relative standard deviations (RSD) lower than 5 % of the different levels prove the precision of the analysis.


Conclusions:
The objective of the study was to determine the water solubility of the test substance "Cadmium selenide". For the complete test substance no single analytical method is available. The water solubility was determined using the flask method and estimated by analysis of the element cadmium using Inductively coupled plasma – atomic emission spectroscopy (ICP-AES).
Preliminary tests and measurements showed fluctuations at room temperature. Therefore it was decided with the sponsor to take different loading rates at 20 ° C rather than to determine the water solubility at different temperatures.
Mean water solubility at 20 °C per loading rate:

100 mg test item / L: Solubility = < 5.7 µg test item / L
1000 mg test item / L: Solubility = < 5.7 µg test item / L

In each of the replicates the water solubility of the test substance was less than the limit of quantification (< 5.7 µg/L) of the analytical method.
Executive summary:

The objective of the study was to determine the water solubility of the test substance"Cadmiumselenide". For the complete test substance no single analytical method is available. The water solubility was determined using the flask method and estimated by analysis of the element cadmium using Inductively coupled plasma – atomic emission spectroscopy (ICP-AES).

Preliminary tests and measurements showed fluctuations at room temperature. Therefore it was decided with the sponsor to take different loading rates at 20 ° C rather than to determine the water solubility at different temperatures.

Mean water solubility at 20 °C per loading rate:

100 mg test item / L:              Solubility = < 5.7 µg test item / L

1000 mg test item / L:           Solubility = < 5.7 µg test item / L

 

In each of the replicates the water solubility of the test substance was less than the limit of quantification (< 5.7 µg/L) of the analytical method.

Description of key information

Cadmium selenide was determined to be insoluble in accordance with the flask method (OECD 105).

Key value for chemical safety assessment

Water solubility:
5.7 µg/L
at the temperature of:
20 °C

Additional information

The objective of the study was to determine the water solubility of the test substance"Cadmiumselenide". For the complete test substance no single analytical method is available. The water solubility was determined using the flask method and estimated by analysis of the element cadmium using Inductively coupled plasma – atomic emission spectroscopy (ICP-AES).

Preliminary tests and measurements showed fluctuations at room temperature. Therefore it was decided with the sponsor to take different loading rates at 20 ° C rather than to determine the water solubility at different temperatures.

Mean water solubility at 20 °C per loading rate:
100 mg test item / L:              Solubility = < 5.7 µg test item / L

1000 mg test item / L:           Solubility = < 5.7 µg test item / L

 

In each of the replicates the water solubility of the test substance was less than the limit of quantification (< 5.7 µg/L) of the analytical method.