Investigation of the photoactivation effect of TiO₂ onto carbon-clay paste electrode by cyclic voltammetry analysis

In this work, a cyclic voltammetry analysis for the detection of Ascorbic Acid (AA) based on a carbon-clay paste electrode modified with titanium dioxide (CPEA/TiO₂) is presented. The electrochemical sensor was prepared using clay and carbon graphite, mixed with TiO₂ to investigate the electrode behavior towards the detection of AA. Comprehensive characterization approaches including X-ray diffraction (XRD), Selected area electron diffraction (SAED), Transmission electron microscopy (TEM), Fourier transform infra-red spectroscopy (FTIR) were carried out on different samples. The results indicated that, the electrode has been effectively modified, while the electrochemical parameters of AA on CPEA/T_iO₂/UV such as the charge transfer coefficient (α ), number of electrons (n) transferred and standard potential were calculated. CPEA/TiO₂/UV exhibit better photoactivity and also higher electronic conductivity under light radiation (100 W). The linear range for AA was determined between 0.150μM and 0.850 μM with the straight-line equation equivalent to $$ (n = 8, R² = 0.993). The limit of detection was 0.732 μM (3σ) and limit of quantification was 2.440 μM. For the analytical applications, pharmaceutical tablets such as Chloroquine phosphate, Azithromycin and Hydroxychloroquine sulfate were performed. In addition, interference study in the analytical application was performed, and it was found that the electroanalytical method used can be well adopted for simultaneous electrochemical detection of AA and Azithromycin.