Amperometric L-cysteine sensor based on a carbon paste electrode modified with Y2O3 nanoparticles supported on nitrogen-doped reduced graphene oxide

We describe an electrochemical sensor for L-cysteine that is based on the use of Y2O3 nanoparticles (Y2O3-NPs) supported on nitrogen-doped reduced graphene oxide (N-rGO). The material was characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and electrochemical methods. Deposited on a carbon paste electrode, the material displays a strongly oxidation peak for L-cysteine at pH 7.0 (compared to an unmodified electrode). The current, measured at a potential 0.7 V (vs. Ag/AgCl), increases linearly in the 1.3 to 720 mu M L-cysteine concentration range, and the detection limit is 0.8 mu M. The sensor was successfully applied to the determination L-cysteine in spiked syrup.