High-throughput isotope analysis of sub-nanogram sized lead using MC-ICP-MS with on-line thallium doping technique and desolvating nebulizer system

Abstract

Copyright © 2021 by The Geochemical Society of Japan. Hattori et al., 2017). However, both the ion detection yield and gain of the MIC detector can change through the long term continuous detection of analytes, and thus, careful monitoring and calibration of gain are necessary to achieve accurate analyses (Paul et al., 2005; Kent, 2008). The development of more convenient, precise isotope analysis of small-sized Pb samples still has great significance in terms of analyses of a large number of samples in geological, geochemical, and environmental studies. The MC-ICP-MS method with thallium (Tl) doping technique (e.g., Hirata, 1996; Collerson et al., 2002; Kamenov et al., 2004; Tanimizu and Ishikawa, 2006) has excellent potential to be used for this purpose. In this method, Pb sample solution doped with a standard Tl is used, and the measured 205Tl/203Tl ratios are utilized for the correction of mass discrimination effects for Pb isotopes during MC-ICP-MS analyses. Precise isotope analysis of sub-nanogram sized Pb sample is potentially achievable by the use of amplifiers with higher resistor and desolvating nebulizer system, which increases electrical signal/noise ratios and sample introduction efficiency, respectively. However, combined use of Tl doping technique and desolvating nebulizer system is not well established. This is because gradual oxidation of Tl+ to Tl3+ occurs under the presence of Pb2+, which causes a change of mass bias factor for Tl isotopes mainly due to preferential transmission of Tl isotopes through the desolvating process (Kamenov et al., 2004). To prevent this effect, Pb isotope measurement must be carried out within an hour after the Tl doping (Kamenov et al., 2004). OtherHigh-throughput isotope analysis of sub-nanogram sized lead using MC-ICP-MS with on-line thallium doping technique and desolvating nebulizer system