Fluorimetric analysis of the nanoceria-mediated oxidation of ampliflu at different pH. a) In the pH range 6–8, the fluorescence intensity at 585 nm increases with time, reaching a plateau after 6 hours (360 mins).In the pH range 1–5, fluorescence starts to develop within the first hours, but decreases right after 100 minutes, reaching zero after 3 hours (180 minutes). b) Photograph taken under UV illumination of vials containing nanoceria within the pH-range 1–8 after 1 or 6 hours of incubation at the corresponding pH.