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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
Study period:
17 July to 20 October 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method A.6 (Water Solubility)
Version / remarks:
Testing used a slow-stir methodology based on Letinski, D.J., Connolly, M.J., Peterson, D.R. and Parkerton, T.F. (2002) “Slow-stir water solubility measurements of selected alcohols and diesters”, Chemosphere, 48, 257 – 265;
Qualifier:
according to guideline
Guideline:
other: Method 105 of the OECD Guidelines for Testing of Chemicals, 27 July 1995
Version / remarks:
Testing used a slow-stir methodology based on Letinski, D.J., Connolly, M.J., Peterson, D.R. and Parkerton, T.F. (2002) “Slow-stir water solubility measurements of selected alcohols and diesters”, Chemosphere, 48, 257 – 265;
GLP compliance:
yes (incl. QA statement)
Type of method:
other: Slow-stir water solubility measurements of selected alcohols and diesters
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 1611081500R Supplied by the Sponsor
- Expiration date of the lot/batch: 08 November 2018
- Purity test date: 99.84%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: approximately 4 °C, in the dark, under nitrogen
- Stability under test conditions: stable
Key result
Water solubility:
0.01 mg/L
Conc. based on:
test mat.
Loading of aqueous phase:
21 mg/L
Incubation duration:
1 079 h
Temp.:
20 °C
pH:
>= 5.7 - <= 6.7
Remarks on result:
other:
Remarks:
mean results of three vessels
Key result
Water solubility:
0.011 mg/L
Conc. based on:
test mat.
Loading of aqueous phase:
21 mg/L
Incubation duration:
1 079 h
Temp.:
20 °C
pH:
6.3
Remarks on result:
other:
Remarks:
vessel 1
Key result
Water solubility:
0.011 mg/L
Conc. based on:
test mat.
Loading of aqueous phase:
21 mg/L
Incubation duration:
1 079 h
Temp.:
20 °C
pH:
>= 6.3 - <= 6.4
Remarks on result:
other:
Remarks:
vessel 2
Key result
Water solubility:
0.01 mg/L
Conc. based on:
test mat.
Loading of aqueous phase:
21 mg/L
Incubation duration:
1 271 h
Temp.:
20 °C
pH:
>= 6.3 - <= 6.4
Remarks on result:
other:
Remarks:
vessel 3
Details on results:
The preliminary estimate of water solubility was 4.7 x 10-5 g/L at 25 °C.

The results from the triplicate vessels established for the determination are summarized in the following table:

 

Vessel 1

Vessel 2

Vessel 3

Mean Concentration at Saturation Equilibrium (g/L)

1.10 x 10-5

1.05 x 10-5

9.64 x 10-6

Standard Deviation of Values Used in the Mean (n = 5)

8.54 x 10-7

1.38 x 10-6

7.26 x 10-7

Percentage Relative Standard Deviation of Values Used in the Mean

7.78%

13.2%

7.54%

Overall Mean Concentration at Saturation Equilibrium (g/L)

1.04 x 10-5

The results from the three individual vessels are presented below in Tables 2 -4 attached in the background material section

Conclusions:
The water solubility of the test item has been determined to be 1.04 x 10-5 g/L of solution at 20.0 ± 0.5 °C.
Executive summary:

The water solubility of 2 -ethylhexylal was performed using a slow-stir methodology based on Letinski, D.J., Connolly, M.J., Peterson, D.R. and Parkerton, T.F. (2002) “Slow-stir water solubility measurements of selected alcohols and diesters”, Chemosphere, 48, 257 – 265; in order to satisfy the data endpoint requirements of Method A6 Water Solubility of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 105 of the OECD Guidelines for Testing of Chemicals, 27 July 1995.

The test system consisted of purified water with a resistivity of greater than 15MΩ. Test vessals were allowed to equilibrate (statically) to the test temperature ( 20.0 ± 0.5 °C) for a period of 3.5 hours prior to the addition of the test item. After the test item had been added to the vessals, at a loading rate of ca. 21 mg/L, stirring started. The stirring speed was such that no physical vortex was visible on the surface of the solutions. The test vessels were protected from light during stirring.

For sampling, stirring was stopped and the first approximately 25 mL of solution was dispensed to waste as this may contain a volume of solution from the tap which was not at equilibrium with the main bulk of each sample solution. Although this volume was not used for chemical analysis, it was used to record the pH of each sampling timepoint.

The required volume of sample solution needed for analysis was then taken directly into a measuring cylinder, in which the extraction procedure was completed, to avoid the need to transfer saturated solutions into further vessels. 

Following sampling for analysis, stirring was re-started. All three vessels in the definitive test were analyzed until a saturation plateau was confirmed analytically for each individual vessel (at 1079 -1271 hours).

The concentration of test item in the sample solutions was determined by gas chromatography mass spectroscopy (GC-MS).

The water solubility of the test item was determined to be 1.04 x 10-5g/L of solution at 20.0 ± 0.5 °C.

Description of key information

In a first test done by Streit (2011), prior to water solubility determination, analytical method for the determination of 2 -ethylhexylal in water has been investigated by 4 different instruments: UV/VIS spectrometry and HPLC coupled with DAD detection, CoronaCAD and MS detection.

The accurate water solubility of the test substance, 2-ethylhexylal, could not be determined and is under the limit of detection of the HPLC-MS method (<1mg/L). The conclusion of the expert statement is that the water solubility of the test substance, 2-ethylhexylal, could not be determined.

In a second test (done in 2017), the water solubility of 2-Ethylhexylal was determined to be 1.04 x 10-5 g/L of solution at 20.0 ± 0.5 °C. Testing used a slow-stir methodology based on Letinski, D.J., Connolly, M.J., Peterson, D.R. and Parkerton, T.F. (2002) “Slow-stir water solubility measurements of selected alcohols and diesters”, Chemosphere, 48, 257 – 265; in order to satisfy the data endpoint requirements of Method A6 Water Solubility of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 105 of the OECD Guidelines for Testing of Chemicals, 27 July 1995.The slow-stirring method is optimal for low solubility liquid substances and may be preferential to the flask procedure (OECD 105 or equivalent) as this may be prone to contamination of the saturated solutions with dispersed micro-droplets of undissolved test item, thus leading to a systematic overestimation of the water solubility value. This approach is recommended by regulatory guidelines

The results from the triplicate vessels established for the determination are summarized in the following table:

 

Vessel 1

Vessel 2

Vessel 3

Mean Concentration at Saturation Equilibrium (g/L)

1.10 x 10-5

1.05 x 10-5

9.64 x 10-6

Standard Deviation of Values Used in the Mean (n = 5)

8.54 x 10-7

1.38 x 10-6

7.26 x 10-7

Percentage Relative Standard Deviation of Values Used in the Mean

7.78%

13.2%

7.54%

Overall Mean Concentration at Saturation Equilibrium (g/L)

1.04 x 10-5

Key value for chemical safety assessment

Water solubility:
0.01 mg/L
at the temperature of:
20 °C

Additional information