High‐precision isotopic characterization of USGS reference materials by TIMS and MC‐ICP‐MS

Abstract

The Pacific Centre for Isotopic and Geochemical Research (PCIGR) at the University of British Columbia has undertaken a systematic analysis of the isotopic (Sr, Nd, and Pb) compositions and concentrations of a broad compositional range of U.S. Geological Survey (USGS) reference materials, including basalt (BCR‐1, 2; BHVO‐1, 2), andesite (AGV‐1, 2), rhyolite (RGM‐1, 2), syenite (STM‐1, 2), granodiorite (GSP‐2), and granite (G‐2, 3). USGS rock reference materials are geochemically well characterized, but there is neither a systematic methodology nor a database for radiogenic isotopic compositions, even for the widely used BCR‐1. This investigation represents the first comprehensive, systematic analysis of the isotopic composition and concentration of USGS reference materials and provides an important database for the isotopic community. In addition, the range of equipment at the PCIGR, including a Nu Instruments Plasma MC‐ICP‐MS, a Thermo Finnigan Triton TIMS, and a Thermo Finnigan Element2 HR‐ICP‐MS, permits an assessment and comparison of the precision and accuracy of isotopic analyses determined by both the TIMS and MC‐ICP‐MS methods (e.g., Nd isotopic compositions). For each of the reference materials, 5 to 10 complete replicate analyses provide coherent isotopic results, all with external precision below 30 ppm (2 SD) for Sr and Nd isotopic compositions (27 and 24 ppm for TIMS and MC‐ICP‐MS, respectively). Our results also show that the first‐ and second‐generation USGS reference materials have homogeneous Sr and Nd isotopic compositions. Nd isotopic compositions by MC‐ICP‐MS and TIMS agree to within 15 ppm for all reference materials. Interlaboratory MC‐ICP‐MS comparisons show excellent agreement for Pb isotopic compositions; however, the reproducibility is not as good as for Sr and Nd. A careful, sequential leaching experiment of three first‐ and second‐generation reference materials (BCR, BHVO, AGV) indicates that the heterogeneity in Pb isotopic compositions, and concentrations, could be directly related to contamination by the steel (mortar/pestle) used to process the materials. Contamination also accounts for the high concentrations of certain other trace elements (e.g., Li, Mo, Cd, Sn, Sb, W) in various USGS reference materials.

Abrupt drainage cycles of the Fennoscandian Ice Sheet

“…Results obtained for these materials are 143 Nd/ 144 Nd = 0.512113 ±2 (2σ m , n = 64) and 143 Nd/ 144 Nd = 0.512991 ±4 (2σ m , n = 16) for JNdi-1 and BHVO-2, respectively. These results are in agreement with previously published data (62,63 Here, e Nd is calculated relative to ( 143 Nd/ 144 Nd) CHUR 0.512638 (64). Uncertainties for e Nd are reported as 2σ.…”

Anthropogenic impacts in North Poland over the last 1300years — A record of Pb, Zn, Cu, Ni and S in an ombrotrophic peat bog

“…The sample solutions were prepared to obtain a beam-intensity in the axial collector ( Pb/ 204 Pb = 15.497 ± 0.002, 206 Pb/ 204 Pb = 16.941 ± 0.002, which are in agreement with the long-term internal laboratory reproducibility (n = ± 1000, 208 Pb/ 204 Pb = 36.713 ± 0.012 (2SD), 207 Pb/ 204 Pb = 15.495 ± 0.004, 206 Pb/ 204 Pb = 16.939 ± 0.004) and literature values (Galer and Abouchami, 1998;Weis et al, 2005Weis et al, , 2006. Although the NIST-SRM 981 Pb standard results were within the error of the triple-spike values after online correction for instrumental mass bias by Tl addition, the sample results were further corrected by the sample-standard bracketing method described by White et al (2000) and Weis et al (2006) (Table 2). One replicate (i.e., a re-run of the same sample solution) of the peat sample 9 and one duplicate (i.e., sample which is processed twice from weighting, acid digestion to analysis) of galena 2 have been analysed.…”

Isotope Ratio Analysis of Lead in Blood and Environmental Samples by Multi-collector Inductively Coupled Plasma Mass Spectrometry

“…21 Rehkamper and Mezger also reported accurate isotope ratio measurements of the Pb standard solution with IsoProbe. 9 Figure 1 shows the Pb isotope ratios in solutions of NIST SRM 981 that contained matrix elements at concentrations 0 -200 mg kg -1 .…”