Modification of a disposable pencil graphite electrode with multiwalled carbon nanotubes: application to electrochemical determination of diclofenac sodium in some pharmaceutical and biological samples

Abstract

A pencil graphite electrode (PGE) modified by multiwalled carbon nanotubes (MWCNTs) was developed as an electrochemical sensor and used for the determination of diclofenac sodium (DIC). The morphological and interfacial properties of the modified electrode were characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) techniques, respectively. Various strategies for modification of the PGE by MWCNTs were examined and concluded that the drop coating of a non-treated PGE (NPGE) has the best performance. In the following, various parameters which affect the electrochemical performance of the modified electrode toward diclofenac sodium determination such as the pH of buffer solution, type and concentration of buffer solution, and amount of MWCNTs on the electrode surface were studied. Differential pulse voltammetry (DPV) was used for the determination of DIC. Under optimized conditions, a calibration graph was plotted by the variation of anodic peak currents as a function of DIC concentration in the linear range of 0.047–12.95 μM with a detection limit of 0.017 μM (S/N = 3). The MWCNTs/PGE was used for the determination of DIC in real samples, including pharmaceutical and biological samples, and the good accuracy of the modified electrode was confirmed by acceptable recovery values.