Electrochemical Behavior and Determination of L-Tyrosine at Single-walled Carbon Nanotubes Modified Glassy Carbon Electrode

Based on single-walled carbon nanotubes (SWCNTs) modified glassy carbon electrode (GCE/SWCNTs), a novel method was presented for the determination of L-tyrosine. The GCE/SWCNTs exhibited remarkable catalytic and enhanced effects on the oxidation of L-tyrosine. In 0.10 mol/L citric acid-sodium citrate buffer solution, the oxidation potential of L-tyrosine shifted negatively from +1.23 V at bare GCE to +0.76 V at GCE/SWCNTs. Under the optimized experimental conditions, the linear range of the modified electrode to the concentration of L-tyrosine was 5.0×10−6–2.0×10−5 mol/L (R1=0.9952) and 2.7×10−5–2.6×10−4 mol/L (R2=0.9998) with a detection limit of 9.3×10−8 mol/L. The kinetic parameters such as α (charge transfer coefficient) and D (diffusion coefficient) were evaluated to be 0.66, 9.82×10−5 cm2 s−1, respectively. And the electrochemical mechanism of L-tyrosine was also discussed.