Multi-walled carbon nanotubes (MWCNTs) were oxidatively functionalized in a mixture of sulfuric acid and nitric acid (3 : 1 v/v) while being ultrasonicated. A simple sensitive electrochemical sensor has been developed for selective determination of tyramine (Tyr) in presence of acetaminophen (Ac) by casting functionalized multi-walled carbon nanotubes (fMWCNT) on the surface of a glassy carbon electrode (GCE). The electrocatalytic oxidation of Ac and Tyr is both individually and simultaneously investigated at the surface of the fMWCNT modified glassy carbon electrode (fMWCNT-MGCE) through using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The electrode is able to completely resolve the voltammetric response of Ac and Tyr from potentially interfering species,e.g. ascorbic acid (AA) and dopamine (DA). By use of DPV, linear calibration curves were obtained for Ac and Tyr over the concentration range up to 100mM and 85mM in 0.1 M buffered solutions (pH 7.0), respectively. The proposed sensor has limits of detection of 0.42mM(3s) for Ac and 0.8mM(3s) for Tyr. Finally, it has been demonstrated that the proposed modified electrode can be successfully used for measuring tyramine and acetaminophen in real samples.
