Electrocatalytic oxidation of tyrosine at poly(threonine)-film modified carbon paste electrode and its voltammetric determination in real samples

The electrochemical behavior of tyrosine on a poly(threonine)-film modified carbon paste electrode was explored in phosphate buffer solution (pH 7.0) using cyclic voltammetric technique. Tyrosine gave an oxidation peak at 687 mV on bare CPE, whereas an oxidation peak at 671 mV with enhanced peak current was obtained on the poly(threonine)-film modified electrode showing the electrocatalytic nature of the modified electrode. Cyclic voltammetric studies indicated that the oxidation of tyrosine at the electrode surface was irreversible, adsorption controlled and involves one electron. Linear calibration plot between the oxidation peak current and the tyrosine concentration was in the range of 5 x 10(-7) to 1 x 10(-5) M and 1 x 10(-5) to 2.0 x 10(-4) M with a correlation coefficient of 0.999 and 0.997, respectively. Detection limit of tyrosine was found to be 1 x 10(-8) M by differential pulse voltammetric technique. The effect of pH and scan rate of tyrosine was studied. The analytical performance of this sensor was evaluated for the detection of tyrosine in real samples. (C) 2012 Elsevier B.V. All rights reserved.