Determination of Nickel, Cobalt, Copper, Thorium and Uranium in High-Purity Zinc Metal by ICP-MS with On-Line Matrix Separation

Abstract

Traces of Co, Cu, Ni, Th and U in high-purity zinc metal were determined by inductively coupled plasma mass spectrometry (ICP-MS) in combination with flow-injection (FI) on-line matrix separation (FI-ICP-MS). The anion-exchange separation method of an HC1 system was applied to the separation of Ni, Co, Cu, Th and U from zinc matrix. The matrix element, zinc, was adsorbed on an anion-exchange (BIORAD AG1-X8) mini-column (2.0 mm i,d.×300 mm bed length), while the analytes were directly introduced into the ICP-MS. The following detection limits (in ng g^-1) were obtained: Ni, 3.1; Co, 1.2; Cu, 4.0; Th, 0.12 and U, 0.48. The reproducibility has proved to be satisfactory with a relative standard deviation of less than 5% (at the 10 ng ml^-1 level, n=3). The method was successfully applied to determining trace impurities in three 6 and 7 nines grade of high-purity zinc metals and in three standard reference materials of high-purity zinc metal samples (from NIST).