Tadalafil electrooxidation on gold and MWCNT-based nanocomposites modified carbon paste electrodes: comparative study and analytical application

The electrochemical behaviour of tadalafil (TAD) was investigated using a solid gold electrode and carbon paste electrodes (CPE) modified with multiwalled carbon nanotubes (MWCNT) or their nanocomposites with noble metal particles (Ag-MWCNT and Au-MWCNT). Cyclic voltammetric study revealed that the oxidation of TAD is irreversible and that adsorption plays a significant role in the oxidation mechanism. Among the investigated electrodes, the Au-MWCNT/CPE exhibited the best electroanalytical performance and was used to develop a sensitive and reliable square-wave adsorptive stripping voltammetric method for TAD determination in Britton-Robinson buffer solution as supporting electrolyte. The optimal pH was 4.0, with target analyte accumulation being most pronounced at Eacc = 0.6 V and tacc = 10 s. Linearity was obtained in the TAD concentration range of 0.10 to 1.96 µg mL-1, with calculated limit of detection of 0.03 µg mL-1. The constructed sensor showed excellent repeatability and reproducibility, as well as anti-interference ability, making it highly suitable for analytical applications, such as the quantification of TAD in the pharmaceutical formulation Cialis® and in human blood serum sample.