Voltammetric Determination of Tryptophan Using a Carbon Paste Electrode Modified with Magnesium Core Shell Nanocomposite and Ionic Liquids

A novel carbon paste electrode modified with ionic liquid (n-hexyl-3-methylimidazolium hexafluoro phosphate) and magnetic coreshell manganese ferrite nanoparticles (MCSILCPE) was fabricated. The electrochemical study of the modified electrode, as well as its efficiency for electro-oxidation of tryptophan, is described. Cyclic voltammetry (CV), choronoamperometry (CHA) and square wave voltammetry (SWV) were used to investigate oxidation of tryptophan in aqueous solution. The diffusion coefficient (D = 3.53 × 10-6 cm2 s-1), was determined using electrochemical approaches. It has been found that under an optimum condition (pH 7.0), the oxidation of tryptophan at the surface of such an electrode occurs at a potential about 150 mV less positive than that of an unmodified carbon paste electrode. SWV exhibits a linear dynamic range from 5.0 × 10-6-4.0 × 10-4 M tryptophan. The morphology of the modified electrode was studied using SEM. The limit of detection was equal to 1.1 × 10-6 M. The electrode was also employed for determination of tryptophan in urine samples.