Electrochemical behavior and voltammetric determination of tryptophan based on 4-aminobenzoic acid polymer film modified glassy carbon electrode.

Herein, a novel electrochemical method was developed for the determination of tryptophan based on the poly(4-aminobenzoic acid) film modified glassy carbon electrode (GCE). The electrochemical behaviors of tryptophan at the modified electrode were investigated. It was found that the oxidation peak current of tryptophan at the modified GCE was greatly improved compared with that at the bare GCE. The effects of supporting electrolyte, pH value, scan rate, accumulation potential and time were examined. The oxidation peak current of tryptophan was proportional to its concentration over the range from 1.0 x 10(-6) to 1.0 x 10(-4)mol L(-1). The limit of detection was evaluated to be 2.0 x 10(-7)mol L(-1). The proposed method was sensitive and simple. It was successfully employed to determine tryptophan in pharmaceutical samples.