Simultaneous determination of copper and lead in ethanol fuel by anodic stripping voltammetry

The presence of trace metals in car fuels plays an important role in the engine maintenance. In addition, these metals contribute for the environmental contamination in big cities and their control is necessary. Square Wave Stripping Voltammetry (SWSV) is a very sensitive technique for elemental trace determination and was applied for ethanol fuel analysis. The first studies were done searching for the best conditions for copper determination in alcoholic medium, utilizing gold electrodes. During these studies, the possibility of the simultaneous determination of copper and lead in the same experiment was observed. Two procedures for the analysis of these metals were adopted: The direct quantification of metals in alcohol–water mixtures and a second way that involves the evaporation of the organic solvent and re-suspension of the ions with water+electrolyte. Good recovery values were obtained for synthetic samples spiked with known amounts of metals. The results obtained for the two methods were in good agreement. The detection limits for copper and lead in 75% ethanol–water ratio solution were calculated as 120 and 235 ng l⁻¹, respectively, for 15-min deposition time.