ELECTROCHEMICAL DETERMINATION OF ACETAMINOPHEN AT THE SURFACE OF A GLASSY CARBON ELECTRODE MODIFIED WITH MULTI-WALLED CARBON NANOTUBE

A multi-walled carbon nanotubes (MWCNTs) film coated glassy carbon electrode (GCE) was fabricated, and the electrochemical behavior of acetaminophen (AAP) was studied in Britton-Robinson (BR) buffer (pH 7.0), using cyclic voltammetry (CV), square-wave voltammetry (SWV) and differential pulse voltammetry (DPV). Cyclic voltammograms of AAP showed enhanced redox responses for the MWCNT/GCE with respect to the bare GCE. The anodic peak potential shifted to less positive values by increasing the pH. The electrochemical oxidation of AAP at MWCNT/GCE was quasi-reversible and diffusion-controlled. Experimental parameters, such as pH, scan rate, SW frequency and step height, were optimized for AAP measurement. Under the optimum pH of 7.0 in 0.1 M BR buffer solution, the DPV anodic peak current showed a linear relation versus AAP concentration in the range of 7.9x10-7 to 3.4x10-4 M with a detection limit of 3.3x10-7 for DPV, and from 6.5x10-7 to 3.5x10-4 M for SWV with a detection limit of 2.1x10-7 (signal to noise = 3). Moreover, this method demonstrated good reproducibility (RSD = 1.3%, n = 10) and long-term stability. These have been applied to the determination of AAP in effervescent dosage samples.