Determination of Trace Lead in Copper by Cathodic Stripping Voltammetry

Abstract

A simple, rapid and sensitive method based on cathodic stripping voltammetry without preliminary separation of the copper matrix is described for the determination of lead at the ng g^-1 level in copper. The sample was decomposed with nitric acid (2+1), and sodium hydroxide was added to prepare a 1 M sodium nitrate electrolyte at pH 2.O. More than 35% of the lead at the ng level in a 1-cm³ aliquot of the electrolyte containing 2 mg of copper was electrodeposited on a platinum anode as lead(IV) oxide at +1.6 V vs. SCE in 25 min. Reproducible differential pulse cathodic stripping curves were obtained by scanning the potential at a rate of 50 mV s^-1 to +0.60 V vs. SCE. The determination of 5 to 50 ng g"¹ of lead in copper wire was achieved with RSDs of ca. 6% (n=5 - 10) within 1 h.