Benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs., para-, sodium salts

Water solubility

Description of key information

Water solubility_OECD 105/EU Method A.6_Shake flask method: 0.255 mg/L at 20 °C

Key value for chemical safety assessment

Water solubility:

0.255 mg/L

at the temperature of:

20 °C

Additional information

There are two studies available for the C20-24 sodium sulfonate (Benzenesulfonic acid, mono-C20-24 (even)-sec-alkyl derivs., para-, sodium salts).

In the key study (Fox, 2015d), the water solubility of the substance was determined using the flask method compatible with OECD Guideline 105 and EU Method A.6 in compliance with GLP. The samples were shaken at a slow speed (50 rpm) for the definitive test to minimize the emulsification that was possible if shaken more vigorously. On completion of the equilibration period, the samples had excess test item present. After the cleanup of the sample, the solutions were visually clear and colorless but had a definitive Tyndall beam effect. As there were no definitive test item peaks in sample chromatography and the peak profile did not match the overall peak profile of the standards, it was decided to take the overall result as a limit value based on the lowest standard (0.255 mg/L) analysed. This gave a worst case scenario. Conclusively, the water solubility of the test item has been determined to be less than 0.255 mg/L of solution at 20.0 ± 0.5 °C.

In another study (Fox, 2015c), the water solubility of the substance was determined according to a procedure compatible with OECD Guideline 105 and EU Method A.6 in compliance with GLP. The flask method was applied as well. However, no definitive water solubility could be estimated and the water solubility was assessed to be loading rate dependent. Thus, the study is considered as disregarded.

Based on the results of the preliminary test, a loading rate for the definitive test was identified (0.1 g/L). On completion of the equilibration period of the definitive test, the samples were slightly cloudy with excess test item present. After the clean-up of the sample, the solutions were visually clear and colourless, no discreet excess test item but had a definitive Tyndall beam effect. The results indicated that most of the test item dispersed within the water and that it would not be possible to determine a definitive water solubility value. This was because all of the excess test item could not be removed and that the dispersed concentration would be loading rate dependent. The test item had the structure of a typical surfactant so that the Critical Micelle Concentration was determined (see Fox, 2015c).

From a loading rate of 0.1 g/L, the concentration of test item remaining in the samples was determined to be 9.03 x 10^-2g/L of solution at 20.0 ± 0.5 °C.