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Water solubility

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Reference
Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
18.07.2018 - 30.07.2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 105 (Water Solubility)
Version / remarks:
1995
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.6 (Water Solubility)
Deviations:
no
GLP compliance:
no
Type of method:
flask method
Key result
Water solubility:
75.4 g/L
Conc. based on:
test mat. (dissolved fraction)
Incubation duration:
>= 24 - <= 72 h
Temp.:
20 °C
pH:
>= 2.9 - <= 3.1

Preliminary Test

The preliminary test of study CSL-18-0142.06 at room temperature showed, that the water solubility of the test item was between 29.0 and 65.3 g/L.

Table: Preliminary test for the water solubility

Amount of test item [mg]

Total volume of added water [mL]

Time in ultrasonic bath [min]

Remark

104.47

0.1

--

not dissolved

0.6

--

not dissolved

1.6

2

not dissolved

3.6

2

dissolved

The solubility of the test item in water at room temperature was estimated to be between 29.0 and 65.3 g/L. Due to this result, the flask method was performed.

Main Test (flask method)

For the main test three flasks were prepared with an amount of test item and water, and one flask only with water. After stirring and centrifugation the aqueous phases were diluted with double distilled water and measured by means of HPLC. The solution of each flask has been measured twice. The values represented in the table are rounded values. The calculation was carried out with the original not rounded values.

Table: Results of the flask method

Flask

1a

2a

3a

4a

measured value [mg/L]

154.5 / 155.6

153.4 / 152.8

144.6 / 144.4

0 / 0

aliquot of the flask [mL]

0.1

0.1

0.1

1

total volume after dilution [mL]

50

50

50

1

water solubility [g/L]

77.2 / 77.8

76.7 / 76.4

72.3 / 72.2

0 / 0

average water solubility [g/L]

77.5

76.6

72.2

0

mean value of the water solubility [g/L]

75.4

0

standard deviation [g/L]

2.8

--

relative standard deviation [%]

3.7

--


To verify the accuracy of the analytical method freshly prepared standard solutions (prepared with the test item) were measured in between the samples of the flask method.

Table: Measurements of standard solutions

Standard solution

(nominal value [mg/L])

Measured value [mg/L]

Repeatability [%]

Ü1 (90.04)

88.27

98.0

88.17

97.9

Ü2 (114.40)

116.37

101.7

108.15

94.5

The recovery rate of the measured standard solutions was in the range from 94.5 % to 101.7 %, which shows a sufficient accuracy of the analytical method.

Conclusions:
The water-solubility of methylhydroquinone using the flask-method was determined to be 75.4 g/L at 20°C.
Executive summary:

According to OECD Test Guideline 105 (1995) and Regulation EC No. 440/2008 Method A.6. the water solubility at 20 °C of the test item Methylhydroquinone was determined to be:

cS = 75.4 g/L, RSD = 3.7 %.

Description of key information

The water-solubility of methylhydroquinone using the flask-method was determined to be 75.4 g/L at 20°C.

Key value for chemical safety assessment

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

Additional information

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