Cyclic Voltammetric Determination of Norepinephrine with Ag-Tryptophan Compound Film Modified Glassy Carbon Electrode

The modified electrode (Ag-Try/GCE) was prepared by electrodeposition of a film of silver and poly-tryptophan on the surface of glassy carbon electrode at the potential range from -0.8 V to 1.8 V (vs.Ag/AgCl) from a solution containing 1.0 mmol·L-1 AgNO3 and 5.58×10-2mol·L-1 tryptophan. The surface property of the modified electrode was characterized by scanning electron microscopy, and its electrochemical property studied by cyclic voltammetry. It was found that a pair of significant oxidation and reduction peaks of NE was observed at the Ag-Try/GCE with the Epc at 0.306 V and Epa at 0.368 V in PBS of pH 6.0. Based on these findings, a selective method for determination of NE by cyclic voltammetry was proposed. Under the optimized experimental conditions, linear relationship between values of oxidation peak current and concentration of NE was obtained in 2 segmental ranges of 3.4×10-7-8.3×10-6mol·L-1 and 8.3×10-6-1.1×10-4mol·L-1, with detection limit (3S/N) of 4.3×10-8mol·L-1. The proposed method was used in the determination of NE in medicine, giving values of recovery found by standard addition method in the range of 95.6%-99.4%.