Barium Isotopic Compositions of Geological Reference Materials

Abstract

The interest in variations of barium (Ba) stable isotope amount ratios in low and high temperature environments has increased over the past several years. Characterisation of Ba isotope ratios of widely available reference materials is now required to validate analytical procedures and to allow comparison of data obtained by different laboratories. We present new Ba isotope amount ratio data for twelve geological reference materials with silicate (AGV‐1, G‐2, BHVO‐1, QLO‐1, BIR‐1, JG‐1a, JB‐1a, JR‐1 and JA‐1), carbonate (IAEA‐CO‐9) and sulfate matrices (IAEA‐SO‐5 and IAEA‐SO‐6) relative to NIST SRM 3104a. In addition, two artificially fractionated in‐house reference materials BaBe12 and BaBe27 (δ137/134Ba = −1.161 ± 0.049‰ and −0.616 ± 0.050‰, respectively) are used as quality control solutions for the negative δ‐range. Accuracy of our data was assessed by interlaboratory comparison between the University of Bern and the United States Geological Survey (USGS). Data were measured by MC‐ICP‐MS (Bern) and TIMS (USGS) using two different double spikes for mass bias correction (130Ba–135Ba and 132Ba–136Ba, respectively). MC‐ICP‐MS measurements were further tested for isobaric and non‐spectral matrix effects by a number of common matrix elements. The results are in excellent agreement and suggest data accuracy.

Barium Isotopic Compositions in Thirty‐Four Geological Reference Materials Analysed by MC‐ICP‐MS

“…This is also consistent with the results in the previous study (Nan et al ). Barium isotopic compositions for the USGS igneous rock RMs BCR‐2, BHVO‐2, GSP‐2 and AGV‐1 reported here are within uncertainty of published values (Miyazaki et al , Nan et al , , van Zuilen et al ) (Table ).…”

“…Recently, Zeng et al () analysed Ba isotopic compositions of the carbonate and carbonatite reference materials NIST SRM 915b (with extremely low Ba mass fraction of 2 μg g −1 ) and COQ‐1 (Zeng et al ). There are also some Ba isotope data available for a range of igneous rocks (Miyazaki et al , van Zuilen et al , Nan et al ). However, there is an absence of Ba isotope data for soil and sediment RMs.…”

High‐Precision Barium Isotope Measurements of Carbonates by MC‐ICP‐MS

“…Based on the correlation between the Ba isotopes of Fluka Ba(NO 3 ) 2 and NIST SRM 3104a [Δ 137/134 Ba Fluka‐SRM3104a = 0.015 ± 0.072‰ (van Zuilen et al . )], the calculated δ 137/134 Ba of JCp‐1 reported in Pretet et al . () relative to NIST SRM 3104a is 0.18 ± 0.07‰, which was also consistent with our results within uncertainty.…”

“…The calculation used the ratios of δ 137/134 Ba relative to Fluka Ba(NO 3 ) 2 and Δ 137/134 Ba Fluka‐SRM3104a = 0.015 ± 0.072‰ (van Zuilen et al . ). c δ 137/134 Ba calculated based on mass‐dependent fractionation and δ 138/134 Ba values.…”

“…Although a previous study found that the matrix effect of Ca is not distinct even when the Ca/Ba ratio in the sample solution is as high as 100 with the double‐spike correction (van Zuilen et al . ), further purifying Ba from Ca when Ca/Ba is > 100 is still safe. Figure shows the ratios of the Ca and Sr to Ba in the digested in‐house coral and stalagmite reference materials (USTC‐Coral and USTC‐Stalagmite) and the collected solutions after the first column and after the second column.…”