Division 2.9.1 F1

The hydrolysis rate of purified active substances (usually radiolabelled active substance, > 95 % purity), for each of the pH values 4, 7 and 9, under sterile conditions, in the absence of light, must be determined and reported in accordance with method C 7 of Regulation (EC) No 440/2008. For substances with a low rate of hydrolysis, the rate can be determined at 50 °C, or another appropriate temperature.

If degradation is observed at 50 °C, degradation rate at another temperature must be determined, and an Arrhenius plot must be constructed to permit an estimate to be made of hydrolysis at 20 °C. The identity of hydrolysis products formed and the rate constantly observed, must be reported. The estimated DT₅₀ value must also be reported.