Simple and Sensitive Electrochemical Determination of L-Tryptophan at Electrochemically Activated Glassy Carbon Electrode

Herein, we reported an Activated Glassy Carbon Electrode (AGCE) for the detection of L-tryptophan (Trp). AGCE was made by successive cyclic voltammetric potential scanning of glassy carbon electrode (GCE) from -1.5 V to 2.5 V in 0.1 M pH 7.0 phosphate buffer as a supporting electrolyte. The surface morphology of AGCE and Un-Activated Glassy Carbon Electrode (UGCE) was characterized by a Scanning Electron Microscope (SEM). The voltammetric sensing of Trp is carried out using Cyclic Voltammetry (CV) and Linear Sweep Voltammetry (LSV). The electrochemical properties of the AGCE and UGCE were also examined by CV and Electrochemical Impedance Spectroscopy (EIS). AGCE exhibited enhanced anodic peak current and less overpotential for the oxidation of Trp than UGCE. LSV was used for the quantitative determination of Trp. Two linear ranges were obtained for the determination of Trp using LSV from 2.5 μM – 20.0 μM and 2.0 μM – 100.0 μM. The limit of detection (3σ/m) was 0.098 μM.  The current method was successfully used to detect Trp in urine and healthy human serum.