Division 2.9.2 F1

For compounds with a molar (decadic) absorption coefficient (ε) > 10 (1 × mol^–1 × cm^–1) at a wavelength λ ≥ 290 nm, direct phototransformation in purified (e.g. distilled) water at 20 to 25 °C, of purified active substance usually radio labelled using artificial light under sterile conditions, if necessary using a solubiliser, must be determined and reported. Sensitisers such as acetone must not be used as a cosolvent or solubiliser. The light source must simulate sunlight and be equipped with filters to exclude radiation at wavelengths λ <  290 nm. The identity of breakdown products formed which at any time during the study are present in quantities ≥ 10 % of the active substance added, a mass balance to account for at least 90 % of the applied radioactivity, as well as photochemical halflife must be reported.