New modified multiwalled carbon nanotubes paste electrode for electrocatalytic oxidation and determination of warfarin in biological and pharmaceutical samples

A novel sensor for the determination of warfarin based on a simple and sensitive method was developed on multiwalled-carbon-nanotube modified ZnCrFeO4 carbon paste electrodes (MWCNT/ZnCrFeO4/CPEs). Cyclic voltammetry, differential pulse voltammetry, chronoamperometry, and electrochemical impedance spectroscopy were used to investigate the electrochemical behavior of warfarin at the chemically modified electrode. According to the results, MWCNT/ZnCrFeO4/CPEs showed high electrocatalytic activity for warfarin oxidation, producing a sharp oxidation peak current at about +0.97 vs Ag/AgCl reference electrode at pH = 4.0. The peak current was linearly dependent on warfarin concentration over the range of 0.02-920.0 mu mol/L with a detection limit of 0.003 mu mol/L. In addition, chronoamperometry was also used to determine warfarin's catalytic rate constant and diffusion coefficient at MWCNT/ZnCrFeO4/CPEs. (C) 2016, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.