Redox probes, K3[Fe(CN)6] and K4[Fe(CN)6], and phosphate-buffered saline (PBS), pH 7.4 concentration 0.01 M, were purchased from Sigma-Aldrich. Nimesulide was obtained from Alfa Aesar (ThermoFisher Scientific). Other reagents were purchased from POCh (Gliwice). All reagents were analytical grade. The conductivity of the distilled water was k = 0.05 µS, and the pH = 7.94. A sample of treated sewage was collected from the treatment plant in Dębogórze (Pomerania, Poland). Based on the high-performance liquid chromatography experiment, no nimesulide was present in the sewage. The composition and basic physicochemical parameters are presented in the SI file, Table .