Voltammetric determination of copper and lead in gasoline using sample preparation as microemulsions

A voltammetric method for the determination of Cu(II) and Pb(II) in gasoline using sample preparation as three-component solutions (gasoline: propan- 1 -ol: water, 25:60:15 v/v/v) is proposed. HNO3 was employed as a supporting electrolyte and to allow the use of aqueous inorganic standards for calibration, even if the analyte species originally in gasoline is present as a metallo-organic form. A square-wave anodic sequential determination was used by measuring the stripping current of Cu(II) (at +104 mV) using a glassy carbon electrode (GCE) and, in a second run, measuring the Pb(II) stripping current (at -470 mV) using a bismuth-film deposited on the surface of the GCE. The method allowed the quantification of 1.7 x 10(-9) mol L-1 of Cu and 1.4 x 10(-10) mol L-1 of Pb employing a 1500-s accumulation time. Recovery tests using analyte spiked three-component solutions prepared with commercial gasoline samples enabled recoveries of Cu and Pb from 97 +/- 8 to 102 +/- 5%.