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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:
02 May 2017 - 04 July 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
The determination of water solubility was performed using the slow stirring method adapted from OECD Guideline No 123. This study was considered as reliable without restrictions because it was conducted under GLP.
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study
Qualifier:
according to
Guideline:
other: adapted from OECD Guideline 123
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.6 (Water Solubility)
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 105 (Water Solubility)
Deviations:
no
Principles of method if other than guideline:
In a stirring vessel maintained at 20 +/- 0.5°C, ultra-pure water containing the test item was slow stirred. The stirring rate was adjusted in order to form a minimal vortex. The aim of this method was to prevent the formation of emulsions when saturating water. Emulsions can be formed with the shake flask method and lead to a solubility overestimation. The water solubility was given by the mass concentration of the substance in water when a plateau is reached as a function of time. A second experiment is performed in the same conditions
GLP compliance:
yes (incl. certificate)
Remarks:
2017-01-10
Type of method:
other: slow-stirring method
Water solubility:
ca. 9.99 mg/L
Temp.:
20 °C
pH:
>= 5.22 - <= 6.02
Remarks on result:
other: First determination (vessel 1)
Water solubility:
ca. 6.49 mg/L
Temp.:
20 °C
pH:
>= 4.87 - <= 6.02
Remarks on result:
other: Second determination (vessel 2)
Water solubility:
ca. 9.27 mg/L
Temp.:
20 °C
pH:
>= 4.88 - <= 6.28
Remarks on result:
other: Third determination (vessel 3)
Water solubility:
ca. 11.78 mg/L
Temp.:
20 °C
pH:
>= 4.72 - <= 6.28
Remarks on result:
other: Fourth determination (vessel 4)
Key result
Water solubility:
ca. 9.38 mg/L
Temp.:
20 °C
pH:
>= 4.72 - <= 6.28
Remarks on result:
other: Mean of four solubilities values obtained in four different experiments.

Main test:

Concentrations profiles for vessels 1 and 2:

The following table presents the concentrations (in mg/L) obtained during the study for the two first vessels (the sampling in vessel 2 only started when the concentrations observed in vessel 1 was around the equilibrium):

 Sampling date Vessel 1   Vessel 2
 02/05/2017 14:30  0.39 No sampling
 03/05/2017 08:00  2.66  No sampling
 03/05/2017 13:00  3.00  No sampling
 04/05/2017 08:00  5.10  No sampling
 04/05/2017 13:00  4.11  No sampling
 05/05/2017 08:00  6.13  No sampling
 05/05/2017 13:00  5.18  5.84
 09/05/2017 08:00  8.44  5.95
 09/05/2017 13:00  9.26  6.29
 10/05/2017 08:00  9.24  6.32
 10/05/2017 13:00  9.44  5.51
 11/05/2017 08:00  9.64  6.15
 11/05/2017 13:00  9.67  6.05
 11/05/2017 18:00  9.77  6.36
 12/05/2017 13:00  10.01  6.67
12/05/2017 18:00  10.13  6.38
 15/05/2017 12:00  9.77  6.40
 15/05/2017 17:00  10.03 6.36
 16/05/2017 13:00  10.03  6.65
 17/05/2017 13:00  9.45 6.79
 18/05/2017 09:00  10.67  6.68

These concentrations are presented as a function of time in the figure.

The pH values in both systems were measured at the beginning and at the end of the experiments. The pH values were:

-        6.02 in both systems at the beginning of the experiment.

-       5.22 in vessel 1 and 4.87 in vessel 2 at the end of the experiment.

The pH controlled with the indicator strips for each specimen were between 4.5 and 5 for vessel 1 and 2.

A significant difference was observed between the equilibrium concentrations of vessel 1 and 2 (around 10 mg/L for vessel 1 and 6.5 mg/L for vessel 2). Two more experiments were carried out (vessel 3 and 4) in order to study the repeatablility of the measurement.

Concentrations profiles for vessels 3 and 4:

The following table presents the concentrations (in mg/L) obtained for vessels 3 and 4. The sampling only started after an equilibration time of ten days according to the results obtained with vessel 1:

 Sampling date  Vessel 3  Vessel 4
 26/06/2017 11:00  9.64  10.87
 26/06/2017 16:00  11.53  9.17
 27/06/2017 08:00  9.47  11.60
 27/06/2017 14:00  9.58  11.72
 28/06/2017 08:30  11.56  12.43
 28/06/2017 13:30  7.70  9.19
 29/06/2017 08:00  9.88  12.63
 29/06/2017 13:30  10.21  12.07
 30/06/2017 08:30  9.22  11.02
 30/06/2017 13:30  9.07  11.60
 03/07/2017 10:30 8.82   11.78
 03/07/2017 15:30  9.05  12.42
 

These concentrations are presented as a function of time in the figure.

Th pH values in both systems measured at the beginning and at the end of the experiments were:

- 6.28 in both systems at the beginning of the experiment.

- 4.88 in vessel 3 and 4.72 in vessel 4 at the end of the experiment.

The pH controlled with the indicator strips was 4.5 for all specimen from vessels 3 and 4.

 

Demonstration of equilibrium:

The following table presents the dates when the equilibrium was reached, the equilibrium criteria conclusion and the mean of the five concentrations when the equilibrium state was obtained.

 Criteria Vessel 1  Vessel 2   Vessel 3  Vessel 4

 Equilibrium state declaration

 From 12/05/2017 13h

to 16/05/2017 13h

From 12/05/2017 13h

to 16/05/2017 13h

From 29/06/2017 13h30

to 03/07/2017 15h30 

From 29/06/2017 13h30

to 03/07/2017 15h30 

 Maximum difference observed

in the 5 samples of the

equilibrium state

(must be < 30%)

  Min: 9.77 mg/L

Max: 10.13 mg/L

Difference: 3.6%

Min: 6.36 mg/L

Max: 6.67 mg/L

Difference: 4.8% 

 Min: 8.82 mg/L

Max: 10.21 mg/L

Difference: 14.6%

Min: 11.02 mg/L

Max: 12.42 mg/L

Difference: 11.9% 

   Conclusion

  Equilibrium reached

  Equilibrium reached

 Equilibrium reached

 Equilibrium reached

 Mean of the five samples

 9.99 mg/L

 6.49 mg/L

 9.27 mg/L

 11.78 mg/L

Conclusions:
A significant difference in the equilibrium concentrations was observed between the two first vessels. No particular observation was noticed during the experiments to explain this difference (same chromatographic profiles, pH values, visual aspects).
Two more experiments were carried out in the same conditions in order to obtain a more reliable solubility value. No observation was noticed to explain a difference in the solubility value.
The (E,Z)-2,6-DIMETHYLOCTA-2,4,6-TRIENE solubility in water is thus given by the mean of the values obtained for the four vessels:
(E,Z)-2,6-DIMETHYLOCTA-2,4,6-TRIENE water solubility at 20°C +/- 0.5°C: 9.38 mg/L
This solubility value was calculated considering the sum of the (E,Z) and the (E,E) isomers.
Executive summary:

A study was performed to assess the water solubility of test item (E,Z)-2,6-DIMETHYLOCTA-2,4,6-TRIENE by the slow stirring method.

Four determinations in ultrapure water were carried out. 5 mL of the test item were carefully poured at the top of 250 mL of water thermostated at 20 + 0.5°C. Equilibrium was obtained when the test item concentration reached a plateau. The test item concentrations were monitored by HPLC-DAD. All the calculations were carried out considering the sum of the (E,Z) and the (E,E) isomers.

The (E,Z)-2,6-DIMETHYLOCTA-2,4,6-TRIENE solubility in water at 20°C +/- 0.5°C based on the mean of the four determinations with slow-stirring method was: 9.38 mg/L

Description of key information

The water solubility of (E,Z)-2,6-DIMETHYLOCTA-2,4,6-TRIENE is 9.38 mg/L at 20 °C.

Key value for chemical safety assessment

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

Additional information

A study was performed to measure the water solubility with the slow-stirring method and according to OECD guideline 105 and 123. The result was considered with a reliability of 1 (reliable without restrictions) because it is scientifically acceptable and obtained under GLP.