Determination of Trace Lead in Copper by Cathodic Stripping Voltammetry

Abstract

A simple, rapid and sensitive method based on catholic stripping voltammetry without preliminary separation of the copper matrix is described for the determination of lead at the μg g^-1 level in copper. The sample was decomposed with nitric acid (2+1), and sodium hydroxide was added to prepare a 1M sodium nitrate electrolyte at pH 2.0. More than 35% of the lead at the ng level in a 1-cm³ aliquot of the electrolyte containing 2mg of copper was electrodeposited on a platinum anode as lead(IV) oxide at +1.6V vs. SCE in 25min. Reproducible differential pulse catholic stripping curves were obtained by scanning the potential at a rate of 50mV s^-1 to +0.60V vs. SCE. The determination of 5 to 50μg g^-1 of lead in copper wire was achieved with RSDs of ca. 6% (n=5-10) within 1h.