Development of multi-walled carbon nanotubes modified pencil graphite electrode for the electrochemical investigation of aceclofenac present in pharmaceutical and biological samples

A sensitive and novel chemically modified multi-walled carbon nanotubes modified pencil graphite electrode (MCPGE) has been developed for the electrochemical investigation of aceclofenac (ACF). MCPGE was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Phosphate buffer solution (PBS) of pH 7.0 was used as a suitable electrolytic medium, in which aceclofenac (ACF) exhibited a sensitive adsorption controlled oxidation peaks at +0.12, + 0.32 and + 0.51 V and a reduction peak at - 0.26 V (vs Ag/AgCl). The experimental conditions were optimised by means of investigating the dependence of peak current on solution pH, concentration and scan rate etc. The electrochemical parameters such as surface concentration (Gamma), electron transfer coefficient (alpha) and the standard rate constant (k(s)) were investigated at MCPGE. The oxidative peak currents were varied linearly with concentration in the range between 1 x 10(-6) to 60 x 10(-6) M with a detection limit of 2.6 x 10(-9) M. The UV-Vis absorption spectrum of ACF gave the lambda(max) at 272-273 nm and is attributed to the presence of ACF. The applicability of the MCPGE was illustrated by the determination of ACF present in pharmaceutical and human urine samples.