Determination of Gallium Isotopic Compositions in Reference Materials

Abstract

The interest in the study of gallium (Ga) stable isotope fractionation in low‐ and high‐temperature environments has increased significantly in the last few years. However, a unified reference material (RM) is still lacking for the Ga isotope research community, which hinders interlaboratory comparison between different groups. Consequently, certification of Ga isotopic reference materials for interlaboratory comparison is of high priority. In this study, Ga isotope ratio data for ten geological RMs including silicates, shales and ferromanganese nodules, and two pure Ga RMs including NIST SRM 994 and NIST SRM 3119a reported by three different groups, were determined by MC‐ICP‐MS. Sample matrices of geological RMs were separated by a two‐column separation method with the use of AG MP‐1M and AG 50‐X8 resin, separately, and quantitative recoveries of > 99% Ga were obtained for all geological RMs. Instrumental mass bias was corrected by the combined calibrator‐sample bracketing and internal normalisation model. Validation of the proposed method was performed by analysing synthetic solutions. After normalisation of all available δ71Ga data of geological RMs to a single Ga RM, results obtained in our study are in agreement with previously reported results.

A Review on the Elemental and Isotopic Geochemistry of Gallium

“…Data precisions of better than 0.06‰ (2SD), with a variation in δ 71 Ga values of up to 1.83‰ across different industrial and natural materials were achieved, opening the way for Ga isotopic approaches in various research studies. However, studies using the different purification methods reported inconsistent δ 71 Ga values for certain reference materials (Feng et al., 2019; Kato et al., 2017, Wimpenny et al., 2020; Yuan et al., 2016; Zhang et al., 2016), requiring further study of technique reliability. We performed an international calibration and comparison of δ 71 Ga values for set reference materials, with results indicating that δ 71 Ga values, relative to both the NIST SRM 994 and IPGP‐Ga standard (Feng et al., 2019; Kato et al., 2017, Yuan et al., 2016; Zhang et al., 2016), of our newly purchased reference materials JG‐2, BHVO‐2, and BCR‐2 were consistent with those reported previously by other laboratories (Figures 11 and 12, Table S9).…”

“…Yuan et al (2016) studied the adsorption of Ga on surfaces of calcite and goethite minerals, and found significant Ga isotopic fractionation (up to 1.3‰) during Ga adsorption (Yuan et al, 2018), foreshadowing the potential application of Ga isotopes in tracing and characterizing surface biogeochemical processes. Previous studies have also reported that industrially produced Ga materials are significantly enriched in the heavy isotope relative to geological materials, foretelling the usefulness of Ga isotopes for distinguishing natural from anthropogenic sources (Feng et al, 2019;Kato et al, 2017;Yuan et al, 2016;Zhang et al, 2016). It is thus safe to conclude that Ga isotopes are likely to provide additional clues concerning yet-underconstrained Al behavior and its biogeochemical cycle, and shed new light on other biogeochemical processes in which Ga is involved.…”

“…However, studies using the different purification methods reported inconsistent δ 71 Ga values for certain reference materials (Feng et al., 2019; Kato et al., 2017, Wimpenny et al., 2020; Yuan et al., 2016; Zhang et al., 2016), requiring further study of technique reliability. We performed an international calibration and comparison of δ 71 Ga values for set reference materials, with results indicating that δ 71 Ga values, relative to both the NIST SRM 994 and IPGP‐Ga standard (Feng et al., 2019; Kato et al., 2017, Yuan et al., 2016; Zhang et al., 2016), of our newly purchased reference materials JG‐2, BHVO‐2, and BCR‐2 were consistent with those reported previously by other laboratories (Figures 11 and 12, Table S9). Inter‐laboratory and international calibration of standards should thus be undertaken regularly to test method reliability and to evaluate possible standard heterogeneity or contamination (Feng et al., 2019; Kato et al., 2017; Wimpenny et al., 2020; Yuan et al., 2016; Zhang et al., 2016).…”

“… δ 71 Ga values for geological reference materials, normalized to NIST SRM 994 (a) and IPGP Ga standard (b), respectively (see detailed in Table S9). Data from Feng et al., 2019 (green triangle); Kato et al., 2017 (red box), and Zhang et al., 2016 (purple circle) are also displayed. Blue diamonds are the δ 71 Ga values measured in this study.…”

Geostandards and Geoanalytical Research Bibliographic Review 2019

“…Gallium isotopic compositions of several geological RMs have been analysed by Feng et al . (2019). Geng et al .…”