Lithium Isotopic Ratios by Single-Collector ICP-SFMS: A Critical Evaluation Using Reference Materials

Author(s)

Navarro, Margareth S. ^[1] ; Paula-Santos, Gustavo M. ^{[2, 3, 1]} ; Marteleto, Thais de P. ^[1] ; Enzweiler, Jacinta ^[1]

Affiliation

^[1] Univ Campinas UNICAMP, Inst Geosci, Rua Carlos Gomes 250, BR-13083855 Campinas, SP - Brazil

^[2] Univ Bremen, MARUM Ctr Marine Environm Sci, Leobener Str 8, D-28359 Bremen - Germany

^[3] Univ Bremen, Fac Geosci, Leobener Str 8, D-28359 Bremen - Germany

• Document type: Journal article
• Source: GEOSTANDARDS AND GEOANALYTICAL RESEARCH; JUL 2021.
• Web of Science Citations: 0

Abstract

We deployed a procedure to measure Li isotope ratios on a single-collector sector field inductively coupled plasma mass spectrometer (ICP-SFMS) operated with a desolvation system and a high-sensitivity skimmer cone. Under optimised instrumental acquisition conditions, chromatographically separated analyte solutions containing 1 ng g(-1) of Li provided adequate sensitivity using analogue mode detection for both isotopes, without adverse memory effect. Unprecedented for this isotopic system, we estimated the expanded uncertainty (U; k = 2) associated with the obtained delta Li-7 values to validate the procedure. Were considered as potential contributors to the combined uncertainty estimation (u(c)) the measurement intermediate precision, sample digestion and homogeneity, chromatographic separation, procedural blanks and homogeneity of the bracketing measurement standard (IRMM-016). The estimated U was on average (from results obtained with reference materials) 1.2 parts per thousand (k = 2). This is about twice the intermediate measurement precision (2s) of our data, highlighting the importance of evaluating other measurement uncertainty sources. The delta Li-7 values obtained for nineteen silicate rocks and one natural water agree with published values. We also provide the first delta Li-7 = (1.7 +/- 1.2; 0.7)parts per thousand (mean value +/- U (k = 2); intermediate precision (2s); n = 13) for basalt RM BRP-1. (AU)

• FAPESP's process: 19/14631-9 - Understanding anomalous uranium concentrations in groundwater
• Grantee: Jacinta Enzweiler
• Support type: Regular Research Grants
• FAPESP's process: 16/06114-6 - The Neoproterozoic Earth System and the rise of biological complexity
• Grantee: Ricardo Ivan Ferreira da Trindade
• Support type: Research Projects - Thematic Grants