The enviMass workflow (version 1.0) [15] was applied to process the peak lists. For the two batches of experiments with river Roter Main sediment – for which a blank-control experiment was available – the peak lists of the incubations that contained pharmaceuticals and the corresponding blank-control at the same sampling time were simultaneously imported into enviMass and the blank subtraction routine was applied (tolerance windows:m/z: ±5 m Da; RT: ±0.05 min). Peaks with an at least four time shigher intensity compared to the blank-control were retained to keep the initially spiked pharmaceuticals for further processing.For the experiment with river Gründlach sediment, the blank sub-traction step was omitted due to the lack of a blank experiment.Subsequently, the parent pharmaceuticals and internal standards were filtered using m/z ratios, isotopic patterns, and RT. Finally,peaks with mass differences equal to 13C and Cl isotopologueions and RT within a window of ±0.05 min were assigned to distinguish the components with monoisotopic mass. Only those with an observed 13C isotope peak were consequently retained in the list of “unknowns” for further processing.