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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:
19.11.2008 - 11.02.2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method A.6 (Water Solubility)
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 105 (Water Solubility)
Deviations:
no
GLP compliance:
no
Type of method:
column elution method
Key result
Water solubility:
< 0.1 mg/L
Conc. based on:
test mat. (dissolved fraction)
Temp.:
20 °C
pH:
6.1

Preliminary Visual Estimation of the Water Solubility

Amounts of the test item and water were stirred at room temperature until the mixture appeared dissolved or the water solubility could be estimated to be below 10 mg/L.

Table 1: Appearance of the test mixtures

Amount of the test item (mg)

Total volume (mL)

Appearance of mixture

14.5

100

Undissolved*

9.47

500

Undissolved**

3.76

500

Undissolved**

* After adding the indicated amount of water, the solution was treated with ultrasound for 30 minutes.

** After adding the indicated amount of water, the solution was stirred for two hours and ten minutes at room temperature.

The solubility of the test item in water is below 7.52 mg/L. Therefore the water solubility had to be determined by the “column elution method”.

Column elution method

Individual Conditions
Column 1:

Rotation period of the fraction accumulator:        90 min per fraction

Average fraction volume:                                   17.2 mL

Flow rate:                                                        between 11.3 mL/h and 11.7 mL/h

Duration of sampling:                                        about 46.5 h (31 fractions)

Column 2:

Rotation period of the fraction accumulator:           45 min per fraction

Average fraction volume:                                    16.4 mL

Flow rate:                                                        between 21.3 mL/h and 22.0 mL/h

Duration of sampling:                                        about 48 h (64 fractions)

Column 3 (blank):

Rotation period of the fraction accumulator:           45 min per fraction

Average fraction volume:                                    16.1 mL

Flow rate:                                                        between 20.7 mL/h and 22.0 mL/h

Duration of sampling:                                        about 48 h (64 fractions)

Concentration and pH

Table 2. Column-elution method: Column 1

Fraction No.

V in mL

pH

Water Solubility in µg/L

 Measured concentration in µg/L

24

17.5

6.1

<11.3

 <5.66

25

17.5

6.0

<11.3

 <5.66

26

17.5

6.1

<11.3

 <5.66

27

17.5

6.2

<11.3

 <5.66

28

17.5

6.2

<11.3

 <5.66

According to the guideline the run can be stopped if the concentration of five fractions do not differ more than ±30 % without raising or descending tendency. The content of test item in every fraction was below the detection limit.

Table 3. Column-elution method: Column 2

Fraction No.

V in mL

pH

Water Solubility in µg/L

Measured concentration in µg/L 

53

16.5

6.1

<11.3

 <5.66

54

16.5

6.2

<11.3

 <5.66

55

16.5

6.4

<11.3

 <5.66

56

16.5

6.4

<11.3

 <5.66

57

16.5

6.3

<11.3

 <5.66

The content of test item in every fraction was below the detection limit.

Table 4. Column-elution method: Column 3 (blank)

Fraction No.

V in mL

pH

Water Solubility in µg/L

Measured concentration in µg/L 

53

16.5

6.0

<11.3

 <5.66

54

16.5

6.0

<11.3

 <5.66

55

16.5

6.1

<11.3

 <5.66

56

16.5

6.0

<11.3

 <5.66

57

16.5

5.9

<11.3

 <5.66

According to the guideline, the data of the fractions 1 to 5 were not taken into account for the following evaluation. The values of the water solubility were calculated from fractions 24 to 28 for column 1, from the fractions 53 to 57 for column 2, from the fractions 53 to 57 for column 3.

A recovery of the ‘recheck samples’ was performed and the recovery was found to be between 98.3 % and 110.0 % for the single and mean values, indicating a good accuracy of the analytical method. The performed coating check was successful.

Result Column 1 and Column 2: The water solubility of the test item was determined to be <11.3 µg/L.

Result Column 3: The blank concentration was found to be <11.3 µg/L.

Conclusions:
The water solubility of the test substance was determined to be < 0.1 mg/L.
Executive summary:

The water solubility of the test item was determined according to OECD 105 and Regulation (EC) No. 440/2008 method A.6 using the column elution method with HPLC analysis. 89.9 mg of the test item were dissolved in 100 mL acetone. 25 mL of this solution were added to about 3 g of sea-shore sand and the mixture was shaken. The solvent was then removed under reduced pressure using a rotary evaporator (50 °C, 50 mbar). The dry residues were placed into the columns of the test apparatus, which have afterwards been filled with water (test temperature: 20 °C; water pH at 24.2°C: 6.1). After a swelling time of 2 h the pump was started to rinse the substance coated sand with distilled water. Two identical samples were prepared, one of them was exposed to a flow rate of 12.5 mL/h (column 1), the other one to 25.0 mL/h (column 2). Another experiment was performed according to this procedure (flow rate 25.0 mL/h) but without test item ("blank" = column 3). The aqueous fractions were diluted 0.5 mL to 1 mL with methanol and measured by means of HPLC. The water solubility of the test item was determined to be <0.1 mg/L (<11.3 µg/L) at 20 °C (pH ~ 6.0).

Description of key information

The water solubility of the test substance was determined to be < 0.1 mg/L.

Key value for chemical safety assessment

Additional information

The water solubility of the test item was determined according to OECD 105 and Regulation (EC) No. 440/2008 method A.6 using the column elution method with HPLC analysis. 89.9 mg of the test item were dissolved in 100 mL acetone. 25 mL of this solution were added to about 3 g of sea-shore sand and the mixture was shaken. The solvent was then removed under reduced pressure using a rotary evaporator (50 °C, 50 mbar). The dry residues were placed into the columns of the test apparatus, which have afterwards been filled with water (test temperature: 20 °C; water pH at 24.2°C: 6.1). After a swelling time of 2 h the pump was started to rinse the substance coated sand with distilled water. Two identical samples were prepared, one of them was exposed to a flow rate of 12.5 mL/h (column 1), the other one to 25.0 mL/h (column 2). Another experiment was performed according to this procedure (flow rate 25.0 mL/h) but without test item ("blank" = column 3). The aqueous fractions were diluted 0.5 mL to 1 mL with methanol and measured by means of HPLC. The water solubility of the test item was determined to be <0.1 mg/L (<11.3 µg/L) at 20 °C (pH ~ 6.0) (reference 4.8-1).