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Physical & Chemical properties

Water solubility

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Administrative data

Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
12.2017 - 06.2018
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 105 (Water Solubility)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method A.6 (Water Solubility)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
flask method

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid

Results and discussion

Water solubilityopen allclose all
Water solubility:
193.61 mg/L
Conc. based on:
test mat.
Incubation duration:
ca. 24 h
Temp.:
30 °C
pH:
5
Water solubility:
192.81 mg/L
Conc. based on:
test mat.
Incubation duration:
ca. 24 h
Temp.:
30 °C
pH:
5
Water solubility:
328.39 mg/L
Conc. based on:
test mat.
Incubation duration:
ca. 24 h
Temp.:
30 °C
pH:
5
Water solubility:
314 mg/L
Conc. based on:
test mat.
Incubation duration:
ca. 24 h
Temp.:
30 °C
pH:
5
Water solubility:
413.53 mg/L
Conc. based on:
test mat.
Incubation duration:
ca. 24 h
Temp.:
30 °C
pH:
5
Water solubility:
385.04 mg/L
Conc. based on:
test mat.
Incubation duration:
ca. 24 h
Temp.:
30 °C
pH:
5

Any other information on results incl. tables

Preliminary test

 

The test item was given by means of a 50µL-syringe to 1 L of purified water as presented in the following table.

 

 

Amount of test item

[µL]

Volume of water

 [ml]

Concentration of test item

 [mg/l]

Visual observations

Pre-sample 1

10

1000

12

At first: droplet on the water surface; after shaking: droplet as a greasy film on the glass wall above the water level

+ 10

(20 in sum)

24

greasy film on the glass wall

+ 10

(30 in sum)

36

further 10 µL: fell down as droplet on the bottom of the test flask; at first droplet was clear, after some time it became milky

Pre-sample 2

5

1000

6

After slight shaking the test itemadhered to the glass wall.

 

Due to the strong affinity of the substance to glass surfaces no clear statement about the water solubility could be made. It was decided to proceed with the shake flask method.

 

To largely avoid glass adsorption during the main test, the test item was placed in the test vessel at first and then the water was added.

Main test and results

 

Six samples were prepared with three different test item concentrations in duplicate (see following table).

The samples were shaken at 30 °C (min: 23.05 °C; max: 30.17 °C; mean; 29.51 °C) for 24 h (250 rpm), then equilibrated at 20 ± 0.5 °C for 24 h (gentle shaking). The temperature was controlled at start and end of the equilibration phase (= 20.2 °C).

After this, the samples were taken out of the water bath. The substance adhered to the glass wall in the form of droplets.At the highest test concentration a significant amount of test item could also be seen on the bottom of the vessel.

The aqueous phase was withdrawn with a syringe. The concentration of the test item in the clear aqueous phase of the samples was determined by carbon analysis.

 

Sample no.

Amount of test item

[mg]

Added volume of water

[mL]

Shaking time at 30°C

[h]

Analysed carbon concentration

[mg TOC/L]3)

Concentration of the test item

[mg/L]1)

pH value2)

1

10.45

10

24

101.47

193.61

5

2

11.10

10

24

101.05

192.81

5

3

50.87

10

24

172.11

328.39

5

4

50.86

10

24

165.09

314.0

5

5

100.29

10

24

216.73

413.53

5

6

99.91

10

24

201.80

385.04

5

 

1)calculated from the carbon concentration of the sample solutions and the carbon content of the pure test item (52.41 %)

2)The purified water used for the tests had a pH value of 5.

3)Values could only serve as order of magnitude (for discussion see 9.6)


 

 

Discussion of the results

 

After the preliminary experiments, low water solubility and accordingly low TOC values had been assumed for the test item. The calibration for the TOC measurements had therefore been made in the low concentration range (up to 10 mg/L). However, after performing the measurements overnight, it had to be determined that the TOC values in the measurement solutions were significantly above the calibration range (up to factor 10).

In addition, it had to be noticed that the measurement results for a control solution with a defined TOC content, which was routinely measured before, between and after the test item solutions, were at the exact set point at the beginning of the measurements. In between and after the test item solutions, however, these were significantly above the nominal value and thus also outside the acceptance range of the method (up to 57 %).

As one probable cause of this clear excess carry-over effects from the test item solutions are possible, since the TOC levels in the test item solutions were by a factor in the double-digit range higher than in the control solution.

In addition, the sample injection was performed on the system, inter alia via a glass syringe. The test item had shown a clear affinity for adsorption on glass surfaces in the preliminary experiments.

Beside this, it could be observed that as the amount of the test item used increased, the measured TOC values also increased and did not remain constant as required. This may be due to better water-soluble impurities in the test item (e. g. neodecanoic acid) and / or possible hydrolysis effects.

Repeating of the examinations with the present method is not considered to be expedient, since no additional knowledge is to be expected therefrom.

Consequently, the results obtained in the context of the experiments reported here can only serve as an approximate order of magnitude, but not as exact values. The values do not necessarily represent the water solubility of the test item, but could be due to water-soluble impurities or hydrolysis effects.


Applicant's summary and conclusion

Conclusions:
After the preliminary experiments, low water solubility and accordingly low TOC values had been assumed for the test item. The calibration for the TOC measurements had therefore been made in the low concentration range (up to 10 mg/L). However, after performing the measurements overnight, it had to be determined that the TOC values in the measurement solutions were significantly above the calibration range (up to factor 10).
In addition, it had to be noticed that the measurement results for a control solution with a defined TOC content, which was routinely measured before, between and after the test item solutions, were at the exact set point at the beginning of the measurements. In between and after the test item solutions, however, these were significantly above the nominal value and thus also outside the acceptance range of the method (up to 57 %).
As one probable cause of this clear excess carry-over effects from the test item solutions are possible, since the TOC levels in the test item solutions were by a factor in the double-digit range higher than in the control solution.
In addition, the sample injection was performed on the system, inter alia via a glass syringe. The test item had shown a clear affinity for adsorption on glass surfaces in the preliminary experiments.
Beside this, it could be observed that as the amount of the test item used increased, the measured TOC values also increased and did not remain constant as required. This may be due to better water-soluble impurities in the test item (e. g. neodecanoic acid) and / or possible hydrolysis effects.
Repeating of the examinations with the present method is not considered to be expedient, since no additional knowledge is to be expected therefrom.
Consequently, the results obtained in the context of the experiments reported here can only serve as an approximate order of magnitude, but not as exact values. The values do not necessarily represent the water solubility of the test item, but could be due to water-soluble impurities or hydrolysis effects.
Executive summary:

The water solubility of the test item was determined according to OECD Guideline 105 [adopted on 27 July 1995] and EU test method A.6 [Council Regulation (EC) No 440/2008] with the flask method (modified method).

 

A defined water solubility of the test item could not be determined with the method used.

 

Due to the physico-chemical properties of the test item only an approximate magnitude can be given for the water solubility based on the results obtained during the experiments.The values do not necessarily represent the water solubility of the test item, but could also be due to water-soluble impurities or hydrolysis effects.