Oxidation and detection of L-cysteine using a modified Au/Nafion/glass carbon electrode

In this work, the electrochemical oxidation of L-cysteine (CySH) was investigated on a composite film modified electrode with Au nanoparticles dispersed in the fluorocarbon polymer (Nafion). The excellent electrocatalytic effect on CySH oxidation was attributed to the role of Au nanoparticles. The voltammetric studies revealed two anodic peaks for the oxidation of CySH in the pH range of 2.0-8.0. The electrode was used to detect cysteine at pH 2.0 and pH 7.0. At pH 2.0, a determination range of 3.0-50.0 mu mol/L was obtained with the detection sensitivity of 22.7 mu A/(mmol L-1), while at pH 7.0, a determination range of 2.0-80.0 mu mol/L was obtained with the detection sensitivity of 4.08 mu A/(mmol L-1). The detection limits were estimated to be as low as 1.0 mu mol/L at both pH 7.0 and pH 2.0. Additionally, at pH 7.0, the interferences of ascorbic acid and uric acid were reduced for the detection of cysteine. These made the Au/Nafion/GC electrode a promising candidate for efficient electrochemical sensors for the detection of CySH.