Developing a Sensor for the Simultaneous Determination of Dopamine, Acetaminophen and Tryptophan in Pharmaceutical Samples Using a Multi-Walled Carbon Nanotube and Oxadiazole Modified Glassy Carbon Electrode

The present study describes the electrochemical characteristics of an electrodeposited oxadiazole derivative on multi-walled carbon nanotubes glassy carbon electrode (OMWCNT-GCE) and its role as highly sensitive electrochemical sensor for the electrocatalytic oxidation of dopamine (DA). The surface charge transfer rate constant (k(s)) and the charge transfer coefficient (alpha) for the electron transfer between GCE and electrodeposited oxadiazole were calculated. OMWCNT-GCE exhibited suitable electrocatalytic properties for DA oxidation in a phosphate buffer (pH 7.0) solution. The modified electrode exhibited low limit of detection (0.12 mu mol L-1) for DA. In differential pulse voltammetry (DPV) measurements, OMWCNT-GCE could separate the oxidation peak potentials of DA, acetaminophen (AC) e tryptophan (Trp) present in the same solution, while the bare GCE gave two broad responses. The analytical performance of this sensor was evaluated to determine DA and AC in real samples.