Electrocatalytic oxidation and voltammetric determination of levodopa in the presence of carbidopa at the surface of a nanostructure based electrochemical sensor

In the present paper, the use of a carbon paste electrode modified by meso-tetrakis(3-methylphenyl) cobalt porphyrin (CP) and TiO2 nanoparticles for the determination of levodopa (LD) and carbidopa (CD) was described. Initially, cyclic voltammetry was used to investigate the redox properties of this modified electrode at various scan rates. Next, the mediated oxidation of LD at the modified electrode was described. At the optimum pH of 7.0, the oxidation of LD occurs at a potential about 150 mV less positive than that of an unmodified carbon paste electrode. Based on differential pulse voltammetry (DPV), the oxidation of LD exhibited a dynamic range between 0.1 and 100.0 μM and a detection limit (3σ) of 69 ± 2 nM. DPV was used for simultaneous determination of LD and CD at the modified electrode, and quantitation of LD and CD in some real samples (such as tablets of Parkin-C Fort and Madopar, water, urine, and human blood serum) by the standard addition method.

► Cobalt porphyrin and TiO2 nanoparticles modified electrode was used for the determination of LD in the presence of CD.
► Potential difference between LD and CD is large enough to allow simultaneous determination of LD and CD in mixtures.
► Selectivity, reproducibility and low detection limit, make the modified electrode very useful for accurate determination of LD.