Fig. 3

Chromatographic separation of 1 velpatasvir (IS, 20 µg/mL), 2 nirmatrelvir (20 µg/mL) and 3 ritonavir (20 µg/mL) in an aqueous sample. Chromatographic conditions: Column: Thermo Hypersil ODS C₈ column (250 × 4.6 mm, 5 μm) at 35 °C, Mobile phase: phosphate buffer (50 mM, pH = 3): acetonitrile (35:65, v/v), Elution: Isocratic, Detection: DAD at 210 nm, Flow rate: 1 mL/min, Injection volume: 5 µL