Disposable pencil graphite electrode decorated with a thin film of electro-polymerized 2, 3, 4, 6, 7, 8, 9, 10-octahydropyrimido [1, 2-a] azepine for simultaneous voltammetric analysis of dopamine, serotonin and tryptophan

Abstract

A facile electrochemical sensor for the individual and simultaneous quantification for elevated levels of dopamine, tryptophan, and serotonin was fabricated on pencil graphite electrode modified with 2, 3, 4, 6, 7, 8, 9, 10-octahydropyrimido[1, 2-a] azepine. The fabricated electrode was characterized by scanning electron microscopy and infrared spectroscopy. Voltammetric response of dopamine, tryptophan and serotonin on the electrode was attained by cyclic and differential pulse voltammetric techniques. Under experimental conditions, three well-separated irreversible oxidation peaks at +0.123 V, +0.302 V and +0.619 V were observed correspond to the oxidations of dopamine, serotonin and tryptophan. The anodic peak currents and the concentrations of dopamine, serotonin, and tryptophan were found to be linear in the range from 1 to 20 μM, 1–62 μM, and 1.5–750 μM with detection limits of 0.05, 0.27, and 0.05 μM, respectively. The linear ranges and the limits of detection for the simultaneous determination of these analytes are found to be superior to previously reported electrochemical sensors. The electropolymerization of 2, 3, 4, 6, 7, 8, 9, 10-octahydropyrimido[1, 2-a] azepine on a pencil graphite electrode is reported for the first time and the fabricated electrode is suitable for the determination of dopamine, serotonin and tryptophan in human blood and urine samples with good reproducibility and stability.