Abiotic Degradation (OECD 111)
Abiotic degradation - Hydrolysis as a function of pH
Hydrolysis is an important reaction controlling degradation. The reaction is particularly relevant for substances with low biodegradability and can influence the persistence of a substance in the environment. This method is only applicable to water soluble substances.
The test material is dissolved in water at low concentration with pH and temperature control. The decrease in the concentration over time is measured by a suitable analytical technique. The test is performed at three pH values (normally 4.0, 7.0 and 9.0). The initial testing is performed at 50oC with two further analyses performed at a temperature below this (typically 40oC).
The rate constants for each condition are derived from plots of the log of concentration against time.