▎ 摘　　要

An ultrasensitive electrochemical sensor based on the electrocatalytic properties of nano graphene (nGN) and multiwalled carbon nanotubes (MWCNTs) for the detection of quinidine (QD) in solubilized systems has been developed. This nano graphene-multiwalled carbon nanotube (nGN-MWCNT) composite film modified sensor shows the higher stability and stronger catalytic activity towards oxidation of quinidine and the over-potential decreased significantly compared with the bare glassy carbon electrode (GCE). The electrochemical characterization of the sensor was done by scanning electron microscopy (SEM) and cyclic voltammetry (CV) with working electrode surface area 0.56 cm(2) and diffusion coefficient 2.15 x 10(-3) cm(2) s(-1). Under the optimized conditions, the oxidation peak current of QD is found to be proportional to its concentration in the range of 60 ng-50 mu g with a detection limit of 0.186 ng. The sensor was successfully employed for the detection of quinidine in bulk drugs and in its commercial pharmaceutical formulation. (C) 2013 Elsevier B.V. All rights reserved.