Selective and sensitive spectrofluorimetric quantification of velpatasvir in presence of sofosbuvir. Application to their co-formulated tablet

A new sensitive, rapid and simple spectrofluorimetric method was utilized for the assessment of velpatasvir (VPS) in its bulk form as well as in its combined tablet with sofosbovir (SFV). The technique relies on measuring the native fluorescence of VPS in methanol at 385 nm and 400 nm after excitation at 295 nm. The fluorescence-concentration plots were rectilinear through the range of 2.0-20.0 ng mL^-1 at both emission maxima with lower detection limits of 0.146 ng mL^-1 and 0.378 ng mL^-1, and lower quantification limits of 0.444 ng mL^-1 and 1.147 ng mL^-1 at 385 nm and 400 nm, respectively. The proposed method was appropriately used for the analysis of VPS in its commercial tablet formulation and the results were in good agreement with those achieved with the applied comparison method.