3-ETHYL-5,5-DIMETHYL-GAMMA BUTYROLACTONE

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Test dates: November 3, 2008 to January 8, 2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was conducted according to an internationally recognised method, and under GLP. The substance is adequately identified. Therefore full validation applies.

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

GLP compliance:

yes (incl. QA statement)

Remarks:

GIPC; effective 16 July 2008 (validity 18 months)

Type of method:

flask method

Specific details on test material used for the study:

Storage conditions: Room temperature protected from direct sun light.

Key result

Water solubility:

5 610 mg/L

Conc. based on:

test mat.

Loading of aqueous phase:

6 g/L

Incubation duration:

3 - 5 d

Temp.:

19 °C

pH:

>= 5 - <= 7

Estimated value

QSAR determination gave 1097.3 mg/L at 25°C as te estimated value (EpiSuite, EPA).

Measured value at pH 5

8 tubes were filled with 40 mL of phosphate buffer adjusted to pH 5.27. The tubes were added with 0.25 mL of the test item and rotated for 3 days at the test temperature. Four tubes were sampled on days 1, 2 and 3.

Day	mg/L (+/- SD, n=4)
1	5597.9 (+/- 80.8)
2	5568.4 (+/- 74.6)
3	5612.2 (+/- 51.3)

The water solubility was calculated as mean from days 1, 2 and 3 which fulfilled the validity criteria:

the standard deviation (22.3 mg/L) within the three successive values represented 0.4% of mean value.

Water solubility at pH 5 = 5593 +/- 22 mg/L (rounded values)

pH of the water phase was 5.23 at the end of the test.

The equilibrium in water was achieved within 1 day, and the deletion of the incubation of the solutions at 30°C was justified.

Measured value at pH 7

8 tubes were filled with 40 mL of phosphate buffer adjusted to pH 7.26. The tubes were added with 0.25 mL of the test item and rotated for 5 days at the test temperature. Four tubes were sampled on days 1, 4 and 5.

Day	mg/L (+/- SD, n=4)
1	5650.1 (+/- 109.8)
4	5612.6 (+/- 71.7)
5	5611.8 (+/- 126.5)

The water solubility was calculated as mean from days 1, 4 and 5 which fulfilled the validity criteria:

the standard deviation (21.9 mg/L) within the three successive values represented 0.4% of mean value.

Water solubility at pH 7 = 5625 +/- 22 mg/L (rounded values)

pH of the water phase was 7.23 at the end of the test.

The equilibrium in water was achieved within 1 day, and the deletion of the incubation of the solutions at 30°C was justified.

Measured value at pH 9

8 tubes were filled with 40 mL of phosphate buffer adjusted to pH 9.30. The tubes were added with 0.25 mL of the test item and rotated for 3 days at the test temperature. Four tubes were sampled on days 1, 2 and 3.

Day	mg/L (+/- SD, n=4)
1	3816.0 (+/- 146.4)
4	3987.0 (+/- 206.1)
5	4041.3 (+/- 253.0)

The water solubility was calculated as mean from days 1, 2 and 3 which fulfilled the validity criteria:

the standard deviation (117.6 mg/L) within the three successive values represented 3.0% of mean value.

Water solubility at pH 9 = 3948 +/- 118 mg/L (rounded values)

pH of the water phase was 8.97 at the end of the test.

The equilibrium in water was achieved within 1 day, and the deletion of the incubation of the solutions at 30°C was justified.

Executive summary:

The water solubility of the test substance was determined under GLP based on EU A.6 guideline, flask method.

After preliminary estimation by QSAR calculation, water was equilibrated with slight excess of substance amount, for 3 to 5 days, at 19°C, and 3 different pH, 5, 7 and 9. Concentrations were measured each day using a GC-FID validated method. Individual results fulfilled the validity criteria for reproducibility.

The water solubility of the test item was determined as 5610 mg/L (at 19°C and pH = 5 - 7).

At pH 9, a lower result was recorded (ca 3900 mg/L), and basic hydrolysis was suspected.

Description of key information

Considered soluble, with equilibrium reached within =< 24h, at pH 5 and 7.

Basic hydrolysis suspected at pH 9.

Key value for chemical safety assessment

Water solubility:

5 610 mg/L

at the temperature of:

19 °C

Additional information

A fully reliable experimental study, conducted according to a recognized EC method and under GLP, is available.

It is considered as a key study, and the result is retained as key data.