Direct Determination of Heavy Metals at Picogram per Gram Levels in Greenland and Antarctic Snow by Double Focusing Inductively Coupled Plasma Mass Spectrometry

Abstract

The potential of a double focusing ICP-MS instrument in terms of high sensitivity, sample throughput and low volume of sample consumed was investigated for the direct, simultaneous determination of Co, Cu, Zn, Mo, Pd, Ag, Cd, Sb, Pt, Pb, Bi and U at the low and sub-pg g -1 level in polar snow. The entire analytical procedure, including cleaning of material, field sampling, sample handling, determination of the blanks and instrumental analysis, is described. The mean concentrations detected in snow samples collected in Central Greenland (2.7 m deep pit) are (in pg g -1 ): Co 5.8, Cu 4.6, Zn 47, Mo 1.6, Pd 1.1, Ag 0.60, Sb 0.86, Pt 0.61, Bi 2.5 and U 1.8. The Cd, Pb and U concentrations in a snow core section collected in East Antarctica are: Cd 0.39, Pb 5.0, U 0.04 pg g -1 . Repeatability of measurements ranges between 8 and 25% depending on the element considered. For some of the elements investigated these results constitute the first available for polar snow. The results of direct analysis by double focusing ICP-MS on Cd and Pb in the Antarctic snow samples and on Zn and Cu in Greenland samples are consistent with those obtained by differential pulse anodic stripping voltammetry (DPASV) and graphite furnace atomic absorption spectrometry (GFAAS), respectively.