A sensitive electrochemical sensor is formed by a carbon nanoparticles (CNPs)/glassy carbon electrode for the determination of antidepressant drug fluoxetine in pharmaceutical formulation. The dependence of fluoxetine electro-oxidation currents and potentials on pH concentration and the potential scan rate was studied. Scanning electron microscopy was used for characterisation of the CNPs. The porous layer of the CNPs improved the electroactive surface area and led to a significant increasing in the peak currents, based on the diffusion within a nanoporous film. The best electrochemical response was obtained from differential pulse voltammograms in the buffer solution (pH 9.0). Linear calibration graphs were obtained in 1-25 µM with %RSD values from 0.3 to 5.7 and the detection limit of 0.4 µM (S/N = 3). The CNPs modified electrode was successfully applied for fluoxetine determination in capsules and the results showed sufficient precision and achieved a mean recovery accuracy of 99.06%.

Amlodipine besylate and atorvastatin calcium have been determined by the simultaneous voltammetric method at a multi-walled carbon nanotubes:graphite (MWCNTs:G) paste electrode. In comparison with a glassy carbon electrode, the prepared electrode showed an increase in the peak current because of the high electroactive surface area and excellent electronic conductivity of MWCNTs. The dependence of currents and potentials on pH were investigated for these components at the surface of the MWCNTs:G paste electrode. Differential pulse voltammetry was applied as a sensitive technique for simultaneous determination of the drugs in commercial tablets. By anodic differential pulse voltammetry, the calibration plot was linear in the range of 2.5-100 µg/ml with standard deviation between 2.7-7.1 and 1.8-8.3% for amlodipine and atorvastatin, respectively. The detection limit was 1 µg/ml at the prepared electrode in the buffered solution pH 6.