A graphite-polyurethane composite modified with 2-benzothiazolethiol organofunctionalized silica was evaluated as an alternative electrode in the determination of Cu(2+) ions in ethanol fuel samples, on the basis of a differential pulse anodic stripping voltammetry procedure. This metal can be quantified by mixing ethanol fuel with 0.10 mol L (1) KNO(3) aqueous solution and subsequent voltammetric measurement after the accumulation step. A maximum limit of 70% (v/v) ethanol in potassium nitrate aqueous solution was obtained for voltammetric measurements without loss of sensitivity for metal species. Factors affecting the pre-concentration and stripping steps were investigated and optimum conditions were employed to develop the analytical procedure. Using 20 min of accumulation time, the linear range of 0.1-1.2 mu mol L (1) was obtained with the limit of detection of 3.9 x 10 (8) mol L (1). The developed electrode was successfully applied to determine Cu(2+) in commercial ethanol fuel samples. The proposed method was compared with a traditional analytical technique, the flame atomic absorption spectrometry, and no significant differences between the results obtained by both methods were observed according to statistical evaluation. (C) 2009 Elsevier Ltd. All rights reserved.