Bismuth film electrode for stripping voltammetric measurement of sildenafil citrate

A simple and fast procedure for measuring low concentration of sildenafil citrate (SC), also known as Viagra®, at the ex situ prepared bismuth film electrode (BiFE) is demonstrated. The BiFE was prepared ex situ on the surface of a glassy carbon substrate electrode and employed in adsorptive cathodic stripping voltammetric mode in 0.1 M acetate buffer solution (pH 4.5) in the presence of dissolved oxygen. Electroanalytical properties of the BiFE were studied and compared with the ex situ prepared mercury film electrode, lead film electrode and with bare glassy carbon electrode. The BiFE revealed a LoD (3σ) of 1.8 × 10−8 mol L−1 using 120 s accumulation time and good linear response in the examined concentration range of 1.0 × 10−7 to 1.0 × 10−6 mol L−1 SC with a correlation coefficient (R2) of 0.995 using short accumulation time of 30 s. The obtained very good repeatability of 1.5% (c = 1.0 × 10−6 mol L−1, n = 15) corroborated potential applicability of the BiFE for measuring SC, for example in pharmaceutical formulations. A successful preliminary study using constant current chronopotentiometric stripping mode has been also carried out.