Methyl (R)-2-(4-hydroxyphenoxy)propionate

Water solubility

Description of key information

Campbell et al. (1993): Under the conditions of the study, the water solubility at pH 4, 7, 9 and in Milli RO water was found to be 12.68, 12.89, 13.33 and 13.46 g/L, respectively.

Caesar (1991): Under the conditions of this study, the solubility of the test material in water at 25 ˚C was 21.5 g/L.

Key value for chemical safety assessment

Water solubility:

13.46 g/L

at the temperature of:

20 °C

Additional information

Two studies are available to address this endpoint and both are considered to be key as the data are equally reliable. The studies were assigned a reliability score of 1 in accordance with the criteria for assessing data quality set forth by Klimisch et al. (1997).

Campbell et al. (1993)

The water solubility of the test material was investigated in accordance with the standardised guidelines OECD 105 and EU Method A.6 under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

As an HPLC analytical method was sufficiently sensitive to determine the solubility at the levels indicated by the preliminary test, the flask method was used. Solubility was determined in Milli RO water, pH 4 buffer, pH 7 buffer and pH 9 buffer.

50 mL flasks were prepared in triplicate containing 5 times the quantity of test material required to saturate the solutions, as determined by the preliminary test (i.e. ca. 1.25 g weighed into flask). 25 mL of each buffer solution was added to the appropriate flasks (9 flasks in total per buffer, 36 in all). All flasks were shaken in a thermostatically controlled water bath at 30 °C. One flask from each triplicate set was removed after 24 h and left at the test temperature, 20 °C, for a further 24 h with occasional shaking. The flasks were then sampled into tubes and the samples centrifuged and an aliquot of the supernatant removed for analysis. This procedure of removal from the water bath and acclimatisation was repeated for the other 2 flasks in the set after 2 and 3 days.

Under the conditions of the study, the water solubility at pH 4, 7, 9 and in Milli RO water was found to be 12.68, 12.89, 13.33 and 13.46 g/L, respectively.

Caesar (1991)

The water solubility of the test material was investigated in accordance with the standardised guidelines EU Method A.6 and the Official Gazette of the European Communities L 251/44 ff under GLP conditions using the bulb method.

In this method the test material is dissolved in water at a temperature which is slightly higher than that at which the measurement is to be performed. When saturation has been achieved the solution is cooled and held at the measurement temperature. The concentration of the test material in the aqueous solution, which must not contain any undissolved particles of the test material, is then determined by a suitable analytical method. 

In a preliminary experiment it was established that the solubility of the test material is about 10 g/L at the measurement temperature of 25 °C. The test material was melted at 80 °C in a drying oven, and added to slightly warmed water (35 °C). Three mixtures were prepared with different quantities of water and test material. The mixtures were cooled to ambient temperature and after the phases had separated the saturated aqueous phase was removed. This was then centrifuged for 15 minutes at about 3000 rpm. The supernatant aqueous solution was pipetted off and extracted with chloroform. The concentration of the test material in the chloroform phase was then determined by gas chromatography. The values obtained were recalculated for the aqueous solution from which the extractions had been carried out. All measurements took place under ambient conditions (25 °C).

Under the conditions of this study, the solubility of the test material in water at 25 ˚C was 21.5 g/L.