Construction of europium hexacyanoferrate film and its electrocatalytic activity to tyrosine determination

In this work, a rare-earth metal hexacyanoferrate film, europium hexacyanoferrate film, was electrodeposited on the graphite electrode. For the first time, XPS was employed to confirm that the valences of Fe in the film were changed during the electrochemical reaction, and proper electrochemical equations were proposed. Then, the electrochemical characterization of the film, such as filmthickness, the number of electrons, and the apparent heterogeneous electron transfer rate constant, was deduced from cyclic voltammograms. Furthermore, this film was found to exhibit an electrocatalytic activity to the oxidation of tyrosine. The experimental conditions, pH value and the applied potential, are investigated in detail. At the optimal conditions, the electrocatalytic response is a linear relationship with the concentration of tyrosine in the range of 10 mu M and 0.6 mM, with a detection limit of about 8 mu M. (C) 2009 Elsevier B.V. All rights reserved.