Lithium Isotopic Ratios by Single‐Collector ICP‐SFMS: A Critical Evaluation Using Reference Materials. Issue 4 (26th July 2021)

• Record Type: Journal Article
• Authors: Navarro, Margareth S.; Paula‐Santos, Gustavo M.; Marteleto, Thaís de P.; Enzweiler, Jacinta
• Is Part Of: Geostandards and geoanalytical research. Volume 45:Issue 4(2021)
• Page Start: 701
• Page End: 718
• Publication Date: 2021-07-26
• Subjects: sector field ICP‐MS -- lithium isotopes -- reference materials -- chromatography -- uncertainties; Analytical geochemistry -- Periodicals; Géochimie analytique -- Périodiques; 551.9
• DOI: 10.1111/ggr.12396
• Languages: English
• ISSNs: 1639-4488

Abstract

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 δ 7 Li 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‰ ( k = 2). This is about twice the intermediate measurement precision (2 s ) of our data, highlighting the importance of evaluating other measurement uncertainty sources. The δ 7 Li values obtained for nineteen silicate rocks and one natural water agree with published values. We also provide the first δ 7 Li = (1.7 ± 1.2; 0.7)‰ (mean value ± U ( k = 2); intermediate precision (2 s ); n = 13) for basalt RM BRP‐1. Abstract : Key Points We deployed a procedure to measure Li isotope ratios on a single‐collector ICP‐SFMS, operated under enhanced sensitivity conditions. The mean intermediate precision (0.7‰; 2 s ) obtained for analysed reference materials is comparable to published values. The estimated expanded measurement uncertainty ( U ; k = 2) associated with the δ7Li values was 1.2‰.