Application of 3,4-dihydroxycinnamic acid as a suitable mediator and multiwall carbon nanotubes as a sensor for the electrocatalytic determination of L-cysteine

A highly sensitive electrochemical sensor was prepared for the determination of L-cysteine using a modified multiwall carbon nanotubes paste electrode in the presence of 3,4-dihydroxycinnamic acid (3,4-DHCA) as a mediator, based On an electrocatalytic process. The results indicate that the electrode is electrocatalytically efficient for the oxidation of L-cysteine in the presence of 3,4-DHCA. The interaction between the mediator and L-cysteine can be used for its sensitive and selective determination. Using chronoamperometry, the catalytic reaction rate constant was calculated to be 2.37 x 10(2) mol(-1) L s(-1). The catalytic peak current was linearly dependent on the L-cysteine concentration in the range of 0.4-115 mu mol/L. The detection limit obtained by linear sweep voltammetry was 0.25 mu mol/L. Finally, the modified electrode was examined as a selective, simple, and precise new electrochemical sensor for the determination of L-cysteine in real samples. (C) 2014, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.