Solution and laser ablation MC-ICP-MS lead isotope analysis of gold

Standish, Christopher, Dhuime, Bruno, Chapman, Robert, Coath, Christopher, Hawkesworth, Chris and Pike, Alistair (2013) Solution and laser ablation MC-ICP-MS lead isotope analysis of gold. Journal of Analytical Atomic Spectrometry, 28 (2), 217-221. (doi:10.1039/C2JA30277B).

Abstract

A new approach is presented for the analysis of lead isotopes in gold using solution and laser ablation multi-collector inductively-coupled plasma mass-spectrometry (MC-ICP-MS). Repeat analyses of two gold reference materials (RAuGP3: 34.1 ± 0.5 ppm Pb and RAuGP5: 129 ± 4 ppm Pb, from SPEX CertiPrep Ltd) yield an external reproducibility of <150 ppm for 207Pb/206Pb and 208Pb/206Pb and <250 ppm for 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb for solution analyses after lead separation using a two-stage ion exchange chromatography methodology. External reproducibility of <600 ppm for 207Pb/206Pb and 208Pb/206Pb is achieved for laser ablation analyses. Due to the low abundance of 204Pb and the isobaric interference of mercury, the external reproducibility for 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb is strongly dependant on the 204(Pb + Hg)/202Hg ratio: <1640 ppm when 204(Pb + Hg)/202Hg [similar]1 to 5, <900 ppm when 204(Pb + Hg)/202Hg [similar]5 to 20, and <810 ppm when 204(Pb + Hg)/202Hg >20. Instrumental mass bias is corrected by standard sample bracketing, using NIST SRM981 for solution analyses and NIST SRM610 for laser ablation analyses. Both techniques agree within error, and they have been further demonstrated through the analyses of both geological and archaeological samples: multiple grains from two Irish alluvial gold deposits and samples of two Early Bronze Age Irish gold lunulae. The applicability of these techniques to studies concerning the sources and age of gold mineralisation, and the identification of gold sources exploited in antiquity, is highlighted

This record has no associated files available for download.

Contributors

Author: Christopher Standish

Author: Alistair Pike

Download statistics