Direct Determination of Copper in Biodiesel Using Stripping Analysis

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 µL (0.088 g) of biodiesel, 15 mL of ethanol, and 5 mL of 0.1 mol L−1 HCl aqueous solution. The estimated detection limit was 200 ng g−1 (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.