Estradiol

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

column elution method

Remarks:

at 20°C and 37°C.

Key result

Water solubility:

1.5 mg/L

Temp.:

20 °C

pH:

5.8

Remarks on result:

other: standard deviation: 0.013 mg/L (column elution method)

Water solubility:

2.9 mg/L

Temp.:

37 °C

pH:

5.9

Remarks on result:

other: standard deviation: 0.071 mg/L (column elution method)

Water solubility:

3.7 mg/L

Temp.:

37 °C

pH:

5.7

Remarks on result:

other: standard deviation: 0.7 mg/L (flask method)

Conclusions:

Interpretation of results (migrated information): slightly soluble (0.1-100 mg/L)
The water solubility of the substance is slightly soluble with values of 1.5 mg/L at 20°C and 2.9 mg/L at 37°C.

Executive summary:

According to OECD Guideline for the Testing of Chemicals No. 105 (column elution method) the water solubility of estradiol hemihydrate at 20°C and 37°C was determined using the column elution method, which is based on the elution of the test substance with water from a micro column which is filled with an inert support material (quartz), previously charged with the test substance. The water is continuously circulated through the column until saturation equilibrium is reached as indicated by a practically constant concentration of estradiol. The concentration was monitored by HPLC analysis in samples drawn during the course of equilibration time. Averaging the results from two series of experiments with different flow rates gave water solubilities with 95% confidence interval of 1.5 + 0.005 mg/L at 20°C and 2.9 + 0.029 mg/L at 37°C were determined.

Estradiol hemihydrate can be considered as slightly soluble in water at 20°C in accordance with the descriptive term of EP (5^thed.) and USP 28.

The pH value of the saturated water solutions were determined to be 5.8 at 20°C and 5.9 at 37°C.

Description of key information

The water solubility of the substance is slightly soluble with  values of 1.5 mg/L at 20°C and 2.9 mg/L at 37°C.

Key value for chemical safety assessment

Water solubility:

1.5 mg/L

at the temperature of:

20 °C

Additional information

The solubility at 37 °C was first determined using the tlask method, however, the variance of the results was very large. This was probably caused by small undissolved particles which could not be separated from the solutions. However, the mean value (0.0037 ± 0.0007 g/L) agreed very well with that obtained with the column elution method. The solid state fonn of the insoluble residues corresponded to that of the starting material.