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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:
18 June to 8 October 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method A.6 (Water Solubility)
Qualifier:
according to
Guideline:
OECD Guideline 105 (Water Solubility)
Qualifier:
according to
Guideline:
EPA OPPTS 830.7840 (Water Solubility)
GLP compliance:
yes (incl. certificate)
Remarks:
Hess. Ministerium für Umwelt, Energie, Landwirtschaft und Verbraucherschutz, Wiesbaden, Germany
Type of method:
flask method
Key result
Water solubility:
ca. 1.2 mg/L
Temp.:
20 °C
pH:
ca. 6.32
Key result
Water solubility:
ca. 1 mg/L
Temp.:
20 °C
pH:
ca. 4.01
Key result
Water solubility:
ca. 1 mg/L
Temp.:
20 °C
pH:
ca. 7.02
Key result
Water solubility:
ca. 1.3 mg/L
Temp.:
20 °C
pH:
ca. 9.01

Preliminary estimation

The visual inspections gave the same results using water and the three buffers (pH 4, 7 and 9). Even in a total volume of 1000 mL undissolved particles could still be observed. This result indicated that the solubility in distilled water (as well as at the tested pH values) of the test item was probably below 10 mg/L.

 

The results of the flask method pre-evaluation are reported in the table below.

 

Water/Buffer

Solubility

Measured pH

distilled water

10.74 mg/L

pH 5.39

buffer pH 4

1.41 mg/L

pH 3.99

buffer pH 7

1.71 mg/L

pH 7.00

buffer pH 9

1.86 mg/L

pH 9.03

 

The preliminary results (water solubility < 10 mg/L) suggested the use of column elution method with regard to the main test.

Trials using the column method at pH 4 and in distilled water were carried out. It was observed that the test item was washed off the column. This was shown by solid particles on the surface of the individual fractions. The results obtained were not convincing because no reproducible saturation plateaus were reached. It is believed that the sample material is not sufficiently adsorbed on to the sea sand. Therefore use of the column method as written in the guidelines is unsuitable for the determination of the water solubility. Therefore the determination was carried out using the flask method.

 

Flask method

The water solubility was determined using HPLC at different time intervals for all the four solutions (distilled water and pH buffers). The results, as well as the mean values and the relative standard deviations (RSD) are reported in the table below.

 

Water solubility [mg/L]

Stirring time at 30°C [h]

24

48

72

96

120

144

Average

RSD

Distilled water (pH 6.32)

1.4351

1.2383

1.7235 *

1.1005

1.0574

1.1378

1.2

12.6%

Buffer pH 4.01

1.0195

1.0431

1.0202

0.9738

1.0764

0.9456

1.0

4.7%

Buffer pH 7.02

0.9866

0.9834

0.9877

0.9677

0.9172

1.0245

1.0

3.6%

Buffer pH 9.01

1.3515

1.2789

1.1919

1.2934

1.2169

1.2542

1.3

4.5%

* outlier

Description of key information

Water solubility at 20.0 °C:

1.0 mg/L (RSD 4.7 %) at pH 4.01 (buffer solution)

1.2 mg/L (RSD 12.6 %) at pH 6.32 (distilled water)

1.0 mg/L (RSD 3.6 %) at pH 7.02 (buffer solution)

1.3 mg/L (RSD 4.5 %) at pH 9.01 (buffer solution)

(OECD guideline 105, flask method)

Key value for chemical safety assessment

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

Additional information