Simultaneous determination of ethanol and methanol in fuel ethanol using cyclic voltammetry

► Simultaneous determination of ethanol and methanol in fuel ethanol. ► Fast cyclic voltammetric method identifies adulteration of fuel ethanol. ► The proposed method can be applied for on-site analysis. A new and simple strategy for the simultaneous determination of ethanol and methanol in fuel ethanol using cyclic voltammetry at a gold electrode is reported. A fuel ethanol aliquot was added into an electrochemical cell containing 0.5molL−1 NaOH and 0.1% (v/v) of methanol as the electrolyte and both analytes were determined using cyclic voltammetry. Ethanol was selectively detected at +0.19V and both compounds were detected at +1.20V. Current subtraction (using a correction factor) could be used for the selective determination of methanol. The limits of detection were estimated to be 0.028% and 0.045% (v/v) for ethanol and methanol, respectively. The proposed method presented similar results to those obtained by gas chromatography at a 95% confidence level.