Spectroelectrochemical determination of Levodopa in the presence of interferents on gold nanoparticle-modified FTO electrodes using PARAFAC

Levodopa is the precursor of dopamine neurotransmitter and the principal drug used in the treatment of parkinson’s disease. Different side effects associated with the increase of systemic dopamine due to the enzymatic metabolization of levodopa in peripheral system, necessitates controlling the levels of dopamine and in fact levodopa in patients and therefore a wide variety of methods have been employed for its determination [1, 2]. Spectroelectrochemistry is a new field in analytical chemistry which not only can get the information about the electrochemical behavior of analyte, but its spectroscopic characteristics on the modified or even unmodified transparent working electrodes including mesh electrodes or semiconductor oxides like ITO or FTO [3]. The role of chemometrics in the analysis of spectroelectrochemical data will be cleared by considering the huge amounts of data obtained by spectroelectrochemistry from system under study and that it is an intrinsically trilinear technique [4, 5]. In this study UV-Vis spectroscopy was used in combination with electrochemical techniques like cyclic voltammetry and differential pulse voltammetry for determination of levodopa in the presence of some interfering compounds usually found in pharmaceutical formulations or biological medium during analysis like carbidopa or uric acid. Fluorine-doped tin oxide electrodes modified with electrodeposited gold nanoparticles were used as working electrodes and all experiments were done in a conventional 1-cm quartz cuvette with a homemade Ag/AgCl mini reference electrode and a Pt wire as counter electrode. PARAFAC was used for chemometrics analysis of obtained second order three-way data from standard addition procedure. Analytical figures of merit for determination of levodopa was evaluated and accuracy of method was further ascertained by recovery experiments. The proposed method was successfully applied for determination of levodopa in pharmaceutical samples. Keywords: Spectroelectrochemistry, FTO, Levodopa