Simultaneous detection of L-cysteine and tryptophan as two importantamino acids using a MgO nanostructure-based electrochemical sensor

Modified electro-analytical sensors showed many advantages for the analysis offood, drug, and biological and environmental electro-active compounds [1]. Theapplication of electro-catalytic mechanism to electrochemical analysis sensors canbe increased the selectivity of system [2]. In this work, the synergic effect of MgOnanoparticle (MgO-NPs) and acetylferrocene (AFc) was studied for modification ofcarbon paste electrode (CPE) as a highly sensitive electrochemical sensor forelectro-catalytic determination of L-cysteine in the aqueous solution. A calibrationcurve showed a linear relation in the range of 0.1-700.0 μM. The detection limit 30.0nM was obtained for analysis of L-cysteine at a surface of AF/MgO-NPs/CPE. Figure1 showed differential pulse voltammograms of L-cysteine in the presence oftryptophan with different concentration of two amino acids.The AF/MgO-NPs/CPEshowed two separated oxidation signals with ΔE~170 mV in the solution containingL-cysteine and tryptophan that was sufficient for simulation determination of theseamino acids. The modified electrode was successfully used for the determination ofL- cysteine in real samples.