Ion Exchange Chromatography and Mass Bias Correction for Accurate and Precise Zn Isotope Ratio Measurements in Environmental Reference Materials by MC-ICP-MS

Abstract

Precise and accurate δ 66/64 Zn data for environmental reference materials (RMs) including rocks, sediments, soils and plants are presented in order to improve the metrological traceability and analytical control of Zn isotope ratio determinations in future environmental studies. Previously developed ion exchange chromatography protocols were adjusted to enable faster sample throughput and instrumental mass bias processes were investigated. The improved chromatographic protocol yielded precise and quantitative recoveries (99 ± 7%, σ, n = 16), while the mass bias correction using Cu as external dopant provided precisions better than 0.02‰, 2σ, n = 7. Investigations into spectral and non-spectral interferences identified significant formation of Cr and Ti oxides and hydroxide ionic species. Analysis of six RMs (BHVO-2 basalt (USGS), BCR-2 basalt (USGS), AGV-2 andesite (USGS), 2709 San Joaquin soil (NIST), 1646a estuarine sediment (NIST) and 1573a tomato leaves (NIST)) showed good reproducibility (< 0.01‰, 2σ, 5 ≤ n ≥ 1).

Assessment of the metal contamination evolution in the Loire estuary using Cu and Zn stable isotopes and geochemical data in sediments

“…The Zn ETH standard data are converted to the JMC Lyon values by adding a factor of 0.28‰, as recommended by Archer et al (2017). The use of data reported against JMC standard is advantageous because it allows to compare to most of Zn isotope published data (Araújo et al, 2017c). The error introduced by this conversion is smaller than analytical uncertainty.…”

Zinc isotopes as tracers of anthropogenic sources and biogeochemical processes in contaminated mangroves

“…Before the isotope ratio determinations, Zn was separated from other elements using an ion-exchange chromatography procedure employing a Bio-Rad PolyPrep column filled with 2 ml of the anion exchange resin AG-MP1, 100-200 mesh, (Araújo et al, 2017b). For subsequent mass bias corrections, the Cu standard NIST-976 was added to the purified fractions after the ion exchange procedure and concentration matched with the ratio 1:1 (300 µg ml -1 in 0.05 M HNO 3 ).…”

A global assessment of Zn isotope fractionation in secondary Zn minerals from sulfide and non-sulfide ore deposits and model for fractionation control

“…and co workers (2008) and by Araújo et al (2016). A Cetac Aridus desolvating nebulizer (Cetac Technologies, Omaha) was used for sample introduction.…”