Application of Modified Carbon Quantum Dots/Multiwall Carbon Nanotubes/Pencil Graphite Electrode for Electrochemical Determination of Dextromethorphan

In this paper, highly amino-functionalized fluorescent carbon quantum dots (CDs) were fabricated by hydrothermal carbonization of chitosan at mild temperature. Multiwall carbon nanotubes (MWCNTs) and CD were used in the preparation of working electrode. This sensor was based on a poly (diallyl-dimethyl ammonium chloride)/MWCNT/CD modified pencil graphite electrode for monitoring dextromethorphan (DXM) oxidation signals. The morphology and features of the various modifiers that were formed at the electrode surface investigated by field emission scanning electron microscopy. The modified sensor displayed excellent selectivity toward DXM. Electrochemical methods, such as cyclic voltammetry and differential pulse voltammetry were used for the characterization of sensor. Under the optimal experimental conditions, the current response and the concentration of DXM exhibited a linear relationship in the range of 2-600 μM with the detection limit of 0.2 μM. This sensor was successfully applied to determine DXM in the cough syrups, human urine, and plasma samples.