Amperometric dot-sensors based on zinc porphyrins for sildenafil citrate determination

Three types of zinc porphyrins have been used for the design of carbon paste or diamond paste based amperometric dot-sensors. Sildenafil citrate was determined using these sensors by employing differential pulse voltammetry. The linear concentration range for the proposed electrodes was between 10−11 and 10−4 mol L−1, with the lowest detection limit (2.46 pmol L−1) obtained using the diamond paste dot-sensor modified with zinc-5,10,15,20-tetra(4-sulfophenyl)porphyrin. Sildenafil citrate was determined reliably from its pharmaceutical formulations, namely Viagra with recovery values higher than 93%.

► Zn porphyrines were used for the design of diamond and carbon paste electrochemical dot-sensors. ► The active surface of the sensors was analyzed using the AFM. ► The dot-sensors were used for the assay of sildenafil citrate in pharmaceutical formulations and biological fluids.