Carbon nanotubes paste sensor modified with bismuth film for determination of metallic ions in ethanol fuel

In the present study an anodic stripping voltammetric method using a bismuth film modified carbon nanotubes paste electrode for simultaneous determination of metals Zn 2+ , Cd 2+ and Pb 2+ 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 -1 concentration 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 -1 for Zn 2+ , Cd 2+ and Pb 2+ , respectively. The proposed method was applied in ethanol fuel samples.