Schulze, T.T.SchulzeWeiss, S.S.WeissSchymanski, E.E.SchymanskiOhe, P.C. von derP.C. von derOheSchmitt-Jansen, M.M.Schmitt-JansenAltenburger, R.R.AltenburgerStreck, G.G.StreckBrack, W.W.Brack2022-03-042022-03-042010https://publica.fraunhofer.de/handle/publica/22172610.1016/j.envpol.2009.12.032The pharmaceutical diclofenac (DCF) is released in considerably high amounts to the aquatic environment. Photo-transformation of DCF was reported as the main degradation pathway in surface waters and was found to produce metabolites with enhanced toxicity to the green algae Scenedesmus vacuolatus. We identified and subsequently confirmed 2-[2-(chlorophenyl)amino]benzaldehyde (CPAB) as a transformation product with enhanced toxicity using effect-directed analysis. The EC50 of CPAB (4.8 mg/L) was a factor of 10 lower than that for DCF (48.1 mg/L), due to the higher hydrophobicity of CPAB (log K-ow = 3.62) compared with DCF (log D-ow = 2.04) at pH 7.0.en610363journal article