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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:
19 July 2016 to 1 September 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 105 (Water Solubility)
Deviations:
yes
Remarks:
Due to the low solubility, the slow stir method from OECD Test Guideline 123 was adopted.
GLP compliance:
yes (incl. certificate)
Type of method:
flask method
Key result
Water solubility:
90.9 mg/L
Conc. based on:
test mat. (dissolved fraction)
Loading of aqueous phase:
5 g/L
Incubation duration:
6 d
Temp.:
20 °C
pH:
3.7
Remarks on result:
other: The test material is a mixture and this figure represents a water soluble fraction and not that of the entire test substance.
Details on results:
The filtered and unfiltered results were essentially the same; this suggested that the supernatant was a true solution of the test material. A turbidity measurement was performed on a further sample which gave a value of 0.092 NTU (unfiltered). This gave further evidence of a true solution.
The unfiltered solutions gave a mean solubility of 98.21 µg/mL and the filtered solutions gave a mean solubility of 90.90 µg/mL. Due to the nature of the test substance, particulates could be present in the supernatant; therefore the solubility of the filtered solutions were taken to be that of the water solubility.
The water solubility of the test material was 90.90 ± 13 µg/mL; the mean pH of all the solutions was 3.70. The test material is a mixture and the above figure represents a water soluble fraction and not that of the entire test substance.

Table 1: Water Solubility Results

 

Vessel

Concentration (µg/mL)

pH (unfiltered)

Filtered

Unfiltered

Test 1*

1

27.20

25.86

3.74

2

26.47

25.51

3.67

3

0.02

21.85

3.67

Test 2

1

82.31

83.85

3.57

2

77.96

93.36

3.54

3

83.23

93.11

3.53

Test 3

1

95.64

81.68

3.82

2

94.76

99.98

3.84

3

104.95

88.46

3.81

Test 4

1

106.13

114.83

3.61

2

113.35

113.25

3.58

3

96.74

119.88

3.52

Test 5

1

76.04

97.61

3.84

2

79.69

86.76

3.89

3

80.02

105.75

3.82

Mean

 

90.90

98.21

3.70

SD

 

12.68

12.75

 

%RSD

 

13.95

12.98

 

*These results were above the calibration line and therefore are considered indicative and not included in the mean results.

Conclusions:
Under the conditions of the study, the water solubility of the test material was determined to be 90.90 ± 13 µg/mL. The test material is a mixture and this figure represents a water soluble fraction and not that of the entire test substance.
Executive summary:

The water solubilty of the test material was invesigated in a GLP study conducted in accordance to the standardised guideline OECD 105.

Preliminary investigations suggested that the water solubility was very low. For the main test, three slow stir vessels were charged with

double-distilled water (900 mL) and a stirrer bar added.

An aliquot of test material (about 5 g) was carefully added to the surface of the water of each flask, so as not to induce mixing. The flasks were stoppered and placed on stirrer plates in an incubator controlled at 20 ± 0.5 °C. The stirring rate adjusted such that the vortex of test material was about 0.5 cm deep. Samples of the aqueous portion were taken from the drain tap at 7 day intervals until a constant level of test material in the water was established. The dead volume in the tap (about 5 mL) was run to waste and then an aliquot of about 15 mL taken. This aliquot was allowed to stand for 6 days at 20 ± 0.5 °C, before analysis.

An aliquot of the sample was syringe filtered through a 0.45 µm PTFE filter and diluted with THF to be within the calibration line for method SMV (PC) 3201206-01V (WAT). For comparison a non-filtered sample was also diluted to be within the calibration line.

Under the conditions of the study, the water solubility of the test material was determined to be 90.90 ± 13 µg/mL. The test material is a mixture and this figure represents a water soluble fraction and not that of the entire test substance.

Description of key information

Under the conditions of the study, the water solubility of the test material was determined to be 90.90 ± 13 mg/L. The test material is a mixture and this figure represents a water soluble fraction and not that of the entire test substance.

Key value for chemical safety assessment

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

Additional information

The water solubilty of the test material was invesigated in a GLP study conducted in accordance to the standardised guideline OECD 105. The study was assigned a reliability score of 1 in accordance with the criteria for assessing data quality set forth by Klimisch et al. (1997).

Preliminary investigations suggested that the water solubility was very low and that the most appropriate method for the determination of water solubility was the adoption of the slow stir method detailed in OECD Test Guideline 123. For the main test, three slow stir vessels were charged with double-distilled water (900 mL) and a stirrer bar added. An aliquot of test material (about 5 g) was carefully added to the surface of the water of each flask, so as not to induce mixing.

The flasks were stoppered and placed on stirrer plates in an incubator controlled at 20 ± 0.5 °C. The stirring rate adjusted such that the vortex of test material was about 0.5 cm deep. Samples of the aqueous portion were taken from the drain tap at 7 day intervals until a constant level of test material in the water was established. The dead volume in the tap (about 5 mL) was run to waste and then an aliquot of about 15 mL taken. This aliquot was allowed to stand for 6 days at 20 ± 0.5°C, before analysis.

An aliquot of the sample was syringe filtered through a 0.45 µm PTFE filter and diluted with THF to be within the calibration line for method SMV (PC) 3201206-01V (WAT).

The filtered and unfiltered results were essentially the same; this suggested that the supernatant was a true solution of the test material. A turbidity measurement was performed on a further sample which gave a value of 0.092 NTU (unfiltered). This gave further evidence of a true solution.

The unfiltered solutions gave a mean solubility of 98.21 µg/mL and the filtered solutions gave a mean solubility of 90.90 µg/mL. Due to the nature of the test substance, particulates could be present in the supernatant; therefore the solubility of the filtered solutions were taken to be that of the water solubility.

Under the conditions of the study, the water solubility of the test material was determined to be 90.90 ± 13 µg/mL (90.90 mg/L). The test material is a mixture and this figure represents a water soluble fraction and not that of the entire test substance.