Analytical Sciences

Voltammetric Determination of Copper and Lead in Gasoline Using Sample Preparation as Microemulsions

Carlos E. CARDOSO,*^,** Wagner F. PACHECO,** Rangel SARUBI,* Márcio L. N. RIBEIRO,* Pércio A. M. FARIAS,** and Ricardo Q. AUCÉLIO**

*Natural and Technological Science Center, Universidade Severino Sombra, Vassouras, RJ 27700-000, Brazil
**Department of Chemistry, Pontifícia Universidade Católica do Rio de Janeiro (PUC/RJ), Rua Marques de São Vicente, 225, CEP 22453-900, Rio de Janeiro, RJ 22453-900, Brazil

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 × 10^-9 mol L^-1 of Cu and 1.4 × 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%.

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