Curve resolution on overlapped voltammograms for simultaneous determination of tryptophan and tyrosine at carbon paste electrode modified with ZnFe2O4 nanoparticles

Abstract

Tryptophan (Trp) and tyrosine (Tyr) are important amino acids that usually coexist with each other in biological fluids. Therefore the simultaneous determination of them is very important because of their very nearly prop-erties. On the other hand, differential pulse voltammetry studies show a high degree overlapping of voltam-mograms for oxidation of Trp and Tyr. Multivariate curve resolution-alternating least squares (MCR-ALS) with electrochemical methods have been applied to overcome this limitation for simultaneous determination of Trp and Tyr. Electrochemical sensor has been developed by utilizing the ZnFe2O4nanoparticles modified carbon paste electrode. The characterization of the modified electrode was studied using different techniques such as field emission scanning electron microscopy, X-ray diffraction, electrochemical impedance spectroscopy, dif-ferential pulse and cyclic voltammetry methods. Operating conditions were optimized with central composite rotatable design (CCRD) associated with the response surface methodology (RSM). The proposed method under the optimized conditions was used to determine Trp and Tyr with linear ranges of 0.1–200.0μM and 0.4–175.0μM, detection limits of 0.04μM and 0.10μM (S/N = 3), respectively. The method was applied for simultaneous determination of Trp and Tyr in spiked human serum and urine samples.