Preparation and Electrochemical Behaviour of Silver Pentacyanonitrosylferrate Film Modified Glassy Carbon Electrode and Its Electrocatalytic Oxidation to L-cysteine

A glassy carbon (GC) electrode modified with silver pentacyanonitrosylferrate (AgPCNF) film as a redox mediator was fabricated. Cyclic voltammetry was used to study the redox property of AgPCNF modified electrode. The modified electrode showed a well-defined redox couple due to [Ag(I)Fe(III/II)(CN)(5)NO](1-/2-) system. The effects of scan rates, supporting electrolytes and solution pHs were studied on the electrochemical behavior of the modified electrode. The feasibility of using the AgPCNF modified electrode to measure L-cysteine was investigated. It showed an excellent electrocatalytic activity towards the oxidation of L-cysteine and the anodic currents were proportional to the L-cysteine concentration in the range of 0.1 mu M to 20 mu M, the linear regression equation is I(pa)(mu A) = -68.58 - 5.78C(L-cysteine) (mu M), with a correlation coefficient 0.998 for N = 23. The detection limit was down to 3.5 x 10(-8)M (three times the ratio of signal to noise).