Sensor de pasta de nanotubos de carbono modificado com filme de bismuto para determinação de íons metálicos em etanol combustível

Abstract

 

In the present study an anodic stripping voltammetric method using a bismuth film modified carbon nanotubes paste electrode for simultaneous determination of metals Zn²⁺, Cd²⁺and Pb²⁺in ethanol fuel is described. The metallic ions were preconcentrated on the bismuth film in the time and deposition potential of 500 s and -1.2 V and the stripping step was carried out by square wave voltammetry (frequency of 15 Hz, pulse amplitude of 25 mV and potential step of 5 mV). Acetate buffer at 0.1 mol L^-1concentration and pH 4.5 was used as support electrolyte. The method showed linearity including the analytical blank up to 48.39 ?g L^-1 for the metals and the obtained limits of detection were 3.36, 0.32 and 0.47 ?g L^-1for Zn²⁺, Cd²⁺and Pb²⁺, respectively. The proposed method was applied in ethanol fuel samples.