Analytical Sciences

Electrochemical Behavior and Sensitive Determination of L-Tyrosine with a Gold Nanoparticles Modified Glassy Carbon Electrode

Hao CHENG,* Changdong CHEN,* and Shuai ZHANG**

*Department of Biological and Chemical Engineering, Guangxi University of Technology, Liuzhou 545006, P. R. China
**School of Chemistry and Chemical Engineering, Zhaoqing University, Zhaoqing 526061, P. R. China

The electrocatalytic oxidation of L-tyrosine was investigated on a gold nanoparticles self-assembled glassy carbon electrode (gold nanoparticles/cysteamine/glassy carbon) using cyclic voltammetry and differential pulse voltammetry. Cyclic voltammetry was carried out to study the electrochemical oxidation mechanism of L-tyrosine, which showed an irreversible oxidation process at a potential of 0.681 V at a modified electrode and 0.807 V at a bare glassy carbon electrode. The anodic peak current linearly increased with the square root of the scan rate, suggesting that the oxidation of L-tyrosine at this kind of modified electrode is a diffusion-controlled process. A good linear relationship between the oxidation peak current and the L-tyrosine concentration in the range of 1.0 × 10⁻⁷ to 3.0 × 10⁻⁴ mol L⁻¹ was obtained in a phosphate buffer solution at pH 7.0. Good sensitivity, selectivity and stability of the modified electrode make it very suitable for L-tyrosine determination in a commercial amino acid oral solution.

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