Voltammetric determination of tryptophan at graphitic carbon nitride modified carbon paste electrode

Herein, we reported carbon paste electrode modified with graphitic carbon nitride (g–C 3 N 4 –CPE) to determine of tryptophan (Trp) using voltametric techniques. Various spectroscopic and electrochemical techniques were used to characterize the as-synthesized g-C 3 N 4 and the assembled electrodes. The transfer coefficient, rate constant and the diffusion coefficient of Trp in this system were found to be 0.28, 1.9 × 10 4  M −1 s −1 and 3.2 × 10 −5 cm 2 s −1 , respectively. The linear range was obtained for the detection of Trp using LSV is from 0.1 μM to 120 μM at pH 5. The limit of detection (LOD) (3σ/ m ) was 0.085 μM. The demonstrated modified CPE was also effectively used for the detection of Trp in milk with percentage recovery of 98 %–105.2 %. Furthermore, the modified CPE exhibited good repeatability, reproducibility and appropriate selectivity.