On-line electrolytic dissolution for lead determination in high-purity copper by isotope dilution inductively coupled plasma mass spectrometry

A flow injection system combining electrolytic dissolution (ED) and programmable isotope dilution (ID) for determination of lead in high-purity copper by inductively coupled plasma mass spectrometry (ED-ID-ICP-MS) is proposed. ED was performed employing a Teflon chamber in where a gold cathode was placed. Best electrolytic conditions were achieved by using an 1.5 mol L-1 nitric acid as electrolytic solution and applying 2.5 A (dc) current during 4 s. Lead was determined in the electrolytic dissolved sample, which has undergone on-line isotope dilution exploiting binary sampling approach. Isotope dilution was carried out measuring the isotope ratio Pb-206/Pb-208 before and after on-line addition of the Pb-208-enriched solution. Precision of isotope ratio measurements for a sample containing 7-70 mug Ph g(-1) was characterized by relative standard deviation (R.S.D.) of 0.5% (n = 3) and the proposed methodology presented an R.S.D. lower than 4% (n = 9). Accuracy was assessed comparing obtained results with those obtained by conventional dissolution and no significant difference at 95% confidence level was observed. (C) 2003 Elsevier Science B.V. All rights reserved.