Highly sensitive voltammetric sensor based on NiO nanoparticle room temperature ionic liquid modified carbon paste electrode for levodopa analysis

This paper describes the development of 1-methyl-3-butylimidazolium chloride ionic liquid-NiO nanoparticle modified carbon paste electrode (MBICl/NiO/NPs/CPE) for the voltammetric determination of levodopa (l-DOPA) in real samples. We describe the synthesis and characterization of NiO/NPs with different methods such as transmission electron microscopy (TEM); energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The electrochemical oxidation of l-DOPA occurred in a pH-dependent 2e^- and 2H⁺ process, and the electrode reaction followed a diffusion-controlled pathway. The oxidation peak potential of LDOPA on the MBICl/NiO/NPs/CPE appeared at 450 mV, which was about 90 mV decrease of the overpotential compared to that obtained on the traditional carbon paste electrode (CPE) and the oxidation peak current was increased for about 3.0 times. The electrochemical parameter such as charge transfer coefficient (α = 0.73) was calculated. The linear response range and detection limit were found to be 0.7-900 μmol L^{- 1} and 0.4 μmol L^{- 1}, respectively using the differential pulse voltammetry method (DPV). The results showed that the proposed sensor is highly selective, sensitive with a fast response for l-DOPA analysis.