DEVELOPMENT OF A MODIFIED CARBON ELECTRODE WITH IONIC LIQUID AND ITS APPLICATION FOR ELECTROCATALYTIC OXIDATION AND VOLTAMMETRIC DETERMINATION OF LEVODOPA

A carbon paste electrode was modified with the ionic liquid 1-butyl-4-methylpyridinium hexafluoro phosphate and applied for the study of the electrocatalytic oxidation and voltammetric determination of the drug levodopa. The developed modified electrode was characterized using cyclic voltammetry and scanning electron microscopy. The oxidation of levodopa at the surface of a modified electrode occurs at lower potentials than that of an unmodified carbon paste electrode and both an enhancement of the anodic peak current and a signal narrower and better defined with the modified electrode were observed. Accordingly, a method for the determination of levodopa was developed using differential pulse voltammetry, at pH 4 and with an accumulation time of 4 min. The oxidation of levodopa exhibited a dynamic range between 2.4 - 16.6 mu g/mL and detection and quantitation limits of 0.63 and 1.4 mu g/mL, respectively. The method was applied to the determination of levodopa in capsules.