3.2. Identified TPs Sixteen TPs derived from the 9 pharmaceuticals in vestigatedin this study were identified by the integrated screening method(Table 1). Eleven compounds were unequivocally confirmed withreference standards, while molecular structures were proposed forthe remaining 5. Fig. 3 shows the time-trends of the 16 TPs. Thetime-trends of the parent compounds, together with extracted ionchromatograms and mass spectra for both the parent compoundsand the identified TPs are available as Supplementary Material.TPs were identified for all parent pharmaceuticals exceptnaproxen. Although 6-O-desmethylnaproxen has previously beenidentified as a common microbial TP of naproxen [17–19], it was notfound in this study. We attribute this to its further transformationunder aerobic conditions which has been described by Quintanaet al. [18].Three TPs were assigned to bezafibrate. Two TPs (an amideproduct (Bez 223) and 4-chlorobenzoic acid) resulting from thecleavage of the amide bond have been previously documented[10,18], whereas to our knowledge the third TP (Bez 238) has notbeen reported before. Bez 238 is also modified at the amide groupand was predicted by UM-PPS as a second-generation TP. The pres-ence of a carboxyl-group is supported in the mass spectrum by afragment with a neutral CO2-loss (Fig. S3, Supplementary Material).