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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:
2018-10-17 to 2019-01-30
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 105 (Water Solubility)
Qualifier:
according to
Guideline:
EU Method A.6 (Water Solubility)
GLP compliance:
no
Type of method:
flask method
Key result
Water solubility:
0.06 g/L
Conc. based on:
test mat. (dissolved fraction)
Temp.:
20 °C
pH:
ca. 5.4

Preliminary test

In a stepwise procedure, increasing volumes of demineralized water were added at room temperature to a defined amount of the test item. After each addition of an amount of water the mixture was treated with ultrasound for 10 minutes and visually checked for any undissolved particles. Results of the preliminary test are summarized in Table 1.

Table 1: Results of the preliminary test

Amount of test item / mg

Added volume of demineralized water / ml

Total volume of demineralized water / ml

Appearance of mixture

100.5

0.1

0.1

Not dissolved

0.4

0.5

Not dissolved

0.5

1.0

Not dissolved

1.0

2

Not dissolved

8.0

10

Not dissolved

90

100

Not dissolved

Three additional preliminary tests were carried out with specified amounts of the test item and 100 ml and 500 ml demineralized water, respectively. After each addition of an amount of water, the mixture was stirred for 24 hours, and visually checked for any undissolved particles. Results of the second preliminary test are summarized in Table 2.

Table 2: Results of second preliminary test

Amount of test item / mg

Total volume of demineralized water / ml

Appearance of mixture

10.3

100

Not dissolved

14.5

500

Not dissolved

4.1

500

Not dissolved

The preliminary test showed that the water solubility of the test item is < 10 mg/l. According to the preliminary test the water solubility test was performed by the column elution method in a first approach. During the performance of the column elution method, it turned out that the water solubility of the test item must be higher than expected from the preliminary test. Therefore, the column elution method was not applicable, and the water solubility of the test item was determined by the flask method in the main test. Only the data of the flask method were reported.

Flask method

After equilibration time undissolved test item was observed in the flasks of the experiments excluding in the blank experiment. The test item showed two main peaks in GC chromatograms of the standard solutions (test item diluted in acetone). The peak area of the peak at around 6.9 min amounted to about 15-29% of the main peak in the chromatograms of the standard solutions (Table 3). In the chromatograms of the water experiments the peak area of the peak at around 6.9 min amounted to about 44-50% of the main peak (Table 3). For the calculation of the test item concentration in the water solubility experiments both peaks were integrated together.

Table 3: Peak areas of the test item in GC chromatograms of the standard solutions and the water solubility experiments

 

Area peak 1 at around 6.6 min / pA*s

Area peak 2 at around 6.9 min / pA*s

Area of peak 2 compared to peak 1 / %

24 h experiment

105

47.7

45

48 h experiment

105

53

50

72 h experiment

95

42.3

44

Standard 1 (c = 16.65 mg/l)

174

50.5

29

Standard 2 (c = 28.40 mg/l)

306

69.5

23

Standard 3 (c = 45.20 mg/l)

543

57.7

15

The water solubility was calculated from the measured and unrounded concentration values and not from the rounded values in Table 4.

Table 4: Water solubility experiments of the test item

Experiment

24 h experiment

48 h experiment

72 h experiment

Blank experiment (72 h)

Amount of test item / mg

146.1

154.4

147.4

-

Amount of demineralized water / ml

20

20

20

20

Stirring time at 30 °C / h

24

48

72

72

pH at ambient temperature

5.4

5.3

5.4

5.5

Dilution factor

5

5

5

5

Measured concentration / mg/l

11.72 / 12.95

12.13 / 12.32

10.80 / 11.69

- / -

Mean concentration / mg/l

12.33

12.23

11.25

-

Water solubility / g/l

0.062

0.061

0.056

-

The peak at a retention time of about 6.9 min was larger in the water solubility experiments compared to the standard solution in acetone. It is assumed that the increased signal resulted from a component of the test item that was better soluble in water than the main component (peak at 6.6 min). As the peak at a retention time of about 6.9 min did not show an increasing tendency between 24 h and 72 h, it was not assumed to result from hydrolysis of the main component (peak at 6.6 min) of the test item. Small amounts of the component at 6.9 min were observed in chromatograms of blank values. It was assumed that small amounts of the corresponding component (peak at 6.9 min) remained in the sample injector of the GC. As the concentration corresponding to the peak in the blank was below the one of the smallest calibration standard (4.5 mg/l), it was not considered for the calculation of the water solubility of the test item.

The water solubility experiments showed a slightly decreasing tendency of the water solubility over time. According to the quality criteria in guideline (EC) No. 440/2008 A.6., the water solubility values of three experiments of the flask method should not differ more than 15%. Within this study the water solubility values of the three experiments of the flask method differed only 5%. Therefore, despite of a slightly decreasing tendency of the water solubility over time in the experiments, the mean value of the three water solubility experiments was given as final result:

The water solubility of the test item at 20 °C was determined to be 0.060 g/l (± 0.003 g/l).

Conclusions:
The water solubility of the test item at 20 °C was found to be 0.060 g/l ((± 0.003 g/l).
Executive summary:

The water solubility of the test item at a temperature of 20 °C was determined by the flask method according to OECD 105 and found to be 0.060 g/l ((± 0.003 g/l).

Description of key information

The water solubility of the test item at a temperature of 20 °C was determined by the flask method according to OECD 105 and found to be 0.060 g/l ((± 0.003 g/l).

Key value for chemical safety assessment

Water solubility:
0.06 g/L
at the temperature of:
20 °C

Additional information