Thallium Mass Fraction and Stable Isotope Ratios of Sixteen Geological Reference Materials. Issue 3 (24th May 2018)

• Record Type: Journal Article
• Authors: Brett, Alex; Prytulak, Julie; Hammond, Samantha J.; Rehkämper, Mark
• Is Part Of: Geostandards and geoanalytical research. Volume 42:Issue 3(2018)
• Page Start: 339
• Page End: 360
• Publication Date: 2018-05-24
• Subjects: thallium -- stable isotopes -- reference materials -- powder heterogeneity -- sample mass; Analytical geochemistry -- Periodicals; Géochimie analytique -- Périodiques; 551.9
• DOI: 10.1111/ggr.12215
• Languages: English
• ISSNs: 1639-4488

Abstract

Abstract : Thallium stable isotope ratio and mass fraction measurements were performed on sixteen geological reference materials spanning three orders of magnitude in thallium mass fraction, including both whole rock and partially separated mineral powders. For stable isotope ratio measurements, a minimum of three independent digestions of each reference material was obtained. High‐precision trace element measurements (including Tl) were also performed for the majority of these RMs. The range of Tl mass fractions represented is 10 ng g −1 to 16 μg g −1, and Tl stable isotope ratios (reported for historical reasons as ε 205 Tl relative to NIST SRM 997) span the range −4 to +2. With the exception – attributed to between‐bottle heterogeneity – of G‐2, the majority of data are in good agreement with published or certified values, where available. The precision of mean of independent measurement results between independent dissolutions suggests that, for the majority of materials analysed, a minimum digested mass of 100 mg is recommended to mitigate the impact of small‐scale powder heterogeneity. Of the sixteen materials analysed, we therefore recommend for use as Tl reference materials the USGS materials BCR‐2, COQ‐1, GSP‐2 and STM‐1; CRPG materials AL‐I, AN‐G, FK‐N, ISH‐G, MDO‐G, Mica‐Fe, Mica‐Mg and UB‐N; NIST SRM 607 and OREAS14P. Abstract : New Tl mass fraction and isotope ratio data for 16 geological reference materials. Tl isotope ratios (as ε 205 TlSRM997 or δ 205 TlSRM997 in parts per ten thousand) range from −3.5 to +1.8. A minimum test size of 100 mg is recommended even for high Tl mass fraction materials.