Fabrication of two-dimensional chemically reduced graphene oxide nanosheets for the electrochemical determination of epinephrine

A simple and selective electrochemical sensor for the determination of epinephrine (EP) was developed using chemically reduced graphene oxide nanosheets (CRGO). The CRGO nanosheets were prepared using modified Hummer's method and the material was characterized using transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and UV-visible spectroscopy, respectively. The CRGO modified glassy carbon electrode (GCE) was employed for the electrochemical studies on EP using cyclic voltammetry (CV). The modified electrode showed significant catalytic activity compared to GO/GCE and bare GCE. The electron transfer kinetics revealed a two electron transfer for all the electrodes with CRGO/GCE exhibiting a high heterogeneous rate constant (0.127 s-1). The detection was carried out using differential pulse voltammetry (DPV) through reduction of epinephrine chrome to leucoepinephrine chrome. The detection through the electrochemical reduction avoids the interference of similar analytes and improves the selectivity of the sensor. The detection limit was found to be 1.6 mu M with two different linear ranges viz. 10-300 and 400-1300 mu M. Further, the electrode was subjected to stability, reproducibility and interference studies. The reliability of the proposed sensor was tested in the presence of biological serum samples.