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 x 10(-6) - 2.0 x 10(-5) mol/L (R-1 = 0.9952) and 2.7 x 10(-5) - 2.6 x 10(-4) mol/L (R-2 = 0.9998) with a detection limit of 9.3 x 10(-8) mol/L. The kinetic parameters such as a (charge transfer coefficient) and D (diffusion coefficient) were evaluated to be 0.66, 9.82 x 10(-5) cm(2) s(-1), respectively And the electrochemical mechanism Of L-tyrosine was also discussed.