A novel cysteine sensor based on modification of carbon paste electrode by Fe(II)-exchanged zeolite X nanoparticles

An electrochemical sensor based on carbon paste electrode (CPE) modified with iron(II) doped into a synthesized nano-particles of zeolite X (Fe(II)-NX/ZCME) was constructed, which is highly sensitive for detection of cysteine (Cys). The modified electrode showed an excellent electro-activity for oxidation of Cys in phosphate buffer at pH 7.4. It has been found that anodic peak potential of Cys oxidation, compared with the unmodified CPE (UCPE), was shifted towards negative values at the surface of the modified electrode under the optimum condition. The peak current increased linearly with the Cys concentration in the wide range of 5.0 x 10(-9)-3.0 x 10(-3) mol L-1. The very low detection limit was obtained to be 1.5 x 10(-10) mol L-1. Finally, the modified electrode was used as a selective, simple and precise new electrochemical sensor for the determination of Cys in the real samples, such as pharmaceutical and biological fluids. (C) 2015 Elsevier B.V. All rights reserved.