Accurate determination of Pb and Bi contents and Pb isotopic composition in geological and cosmochemical samples by inductively coupled plasma quadrupole mass spectrometry

Abstract

A method for accurately determining Pb and Bi contents in geochemical and cosmochemical solid samples using inductively coupled plasma quadrupole mass spectrometry (ICP–QMS) is described. Pb and Bi contents are determined using isotope dilution and calibration methods, respectively. For this purpose, an accurate determination scheme of Pb isotopic ratios is established using standard-sample bracketing and matrix-matching methods due to the significantly differences of Pb isotope ratios in commercial standard solution, geochemical and cosmochemical samples. Lead is chosen as the most appropriate internal standard element to reduce the matrix effect when determining Bi content. Our developed analytical procedure was applied to geological and cosmochemical reference samples to evaluate the accuracy of our data. The Pb isotopic composition data obtained from this study are in good agreement with the literature values obtained using multicollector inductively coupled plasma mass spectrometry and thermal ionization mass spectrometry, which ensures the accuracy of the Pb isotopic ratios obtained by our method. The Bi content data obtained from this study for a cosmochemical sample are in excellent agreement with neutron activation values in literature.