Simultaneous Electrochemical Determination of Sildenafil Citrate and Tadalafil Using a Multi Walled Carbon Nanotubes Modified Glassy Carbon Electrode by Adsorptive Stripping Linear Sweep Voltammetry

Abstract

AbstractAn adsorptive stripping linear sweep voltammetric method was developed for the simultaneous determination of sildenafil citrate and tadalafil. The voltammetric working electrode was a glassy carbon electrode modified with carboxylic multi‐walled carbon nanotubes. The sensitivity of the developed voltammetric method was significantly increased by this modification. Both analytes spontaneously adsorbed on the modified electrode surface due to their adsorption affinities. The irreversible oxidation signals of both analytes were used as the analytical signals. The electrochemical behaviour of sildenafil citrate and tadalafil was assessed using cyclic voltammetry. The developed voltammetric method was linear in the range of 0.01–0.50 μM with a correlation coefficient of 0.9997 and 0.9985 for sildenafil citrate and tadalafil, respectively. The LOQs of the method for both analytes were 0.010 μM. The intra‐ and inter‐day reproducibility of the method was less than 10% RSD in all cases. The extraction recoveries for both analytes ranged between 83 and 94%. The applicability of the developed voltammetric method were investigated by determining the analyte in two different spiked samples (an energy drink and a traditional herbal product). Furthermore, the described method would represent the first electrochemical approach for the simultaneous detection of sildenafil citrate and tadalafil, providing an available alternative to current chromatographic techniques.