A simple, effective, and low-cost protocol for copper determination in biodiesel, with no sample decomposition, is reported. Samples were diluted in an ethanol-water solution (with HCl as supporting electrolyte) generating a homogeneous mixture at which copper was directly detected using stripping chronopotentiometry using a gold working-electrode. The optimized mixture was 100 mL (0.088 g) of biodiesel, 15 mL of ethanol, and 5 mL of 0.1 mol L À1HCl aqueous solution. The estimated detection limit was 200 ng g À1 (300-s deposition time). The elimination of the sample treatment step offers the possibility of on-site measurements in association with commercially-available portable potentiostats.