Electro chemical determination of tryptophan at glassy carbon Electro demo defied with nitrogen defect-Rich graphitic carbon Nitride

Abstract

In this study, nitrogen defect-rich graphitic carbon nitride was synthesized and used to modify glassy carbon electrode for the electrochemical determination of tryptophan. Nitrogen defect-rich graphitic carbon nitride was prepared by thermally polymerizing graphitic-carbon nitride under inert conditions. The obtained nitrogen defect-rich graphitic carbon nitride was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscope. Cyclic voltammetry was used to further analyze the electrochemical properties of bare glassy carbon electrode, graphitic-carbon nitride modified glassy carbon electrode, and nitrogen defect-rich graphitic carbon nitride modified glassy carbon electrode. It was found that nitrogen defect-rich graphitic carbon nitride modified glassy carbon electrode exhibited superior electrocatalytic oxidation, enhanced anodic peak current, and less overpotential towards tryptophan as compared to graphitic-carbon nitride modified glassy carbon electrode and bare glassy carbon electrode. Experimental parameters such as, scan rate, effect of pH, temperature of polymerization of nitrogen defect-rich graphitic carbon nitride were optimized. The suggested electrode showed excellent repeatability, reproducibility, and a low detection limit. Tryptophan in a milk sample was successfully determined using the produced nitrogen defect-rich graphitic carbon nitride modified glassy carbon electrode with a percentage recovery in the range of 97.0-108%, satisfactory recovery obtained from the demonstrated electrochemical sensor. Under the optimum experimental conditions, the oxidation peak currents had good linear relationship with Tryptophan concentrations in the range of 0.02- 0.20 μM at pH 3.0 and a limit of detection of about 0.0034 μM (3σ/m). In addition, the obtained sensor showed good sensitivity, favorable repeatability, and long term stability. Finally, the proposed electrochemical method has been successfully applied for the determination of Trp in real samples with satisfactory results.