Synergic effect of graphene quantum dots and room temperature ionic liquid for the fabrication of highly sensitive voltammetric sensor for levodopa determination in the presence of serotonin

Levodopa, one of the prescribed medications in Parkinson disease, is electrochemically determined here. A room temperature ionic liquid/graphene quantum dots (GQDs) modified carbon paste electrode (RTIL-GQDs/CPE) was used for the electrochemical determination of levodopa. The electro-oxidation mechanism of levodopa at RTIL-GQDs/CPE was also studied. The obtained data showed that the electro-oxidation of levodopa at the RTIL-GQDs/CPE is greatly facilitated, which is attributed to high electrical conductivity of GQDs and RTIL. The electrochemical oxidation of levodopa at the RTIL-GQDs/CPE is a two proton two electron process. The RTIL-GQDs/CPE showed a good electron mediating behavior followed by well separated oxidation signals of levodopa and serotonin. Square wave voltammetric peak current shows a linear relationship corresponds to the concentrations of levodopa in a linear range of 0.05 to 250.0 mu M with detection limit of 10.0 nM. The RTIL-GQDs/CPE shows excellent ability to determination of levodopa in real samples. (C) 2017 Elsevier B.V. All rights reserved.