High‐precision zinc isotope measurement of chemically different geostandards by multicollector inductively coupled plasma mass spectrometry

Abstract

RationaleZinc isotopes are becoming increasingly applicable in high‐temperature geochemistry, for example in crust–mantle interaction and volatilization‐related processes. The published zinc isotope data for some commonly used reference materials, however, show large interlaboratory offsets. In addition, there is still limited data for zinc isotope compositions of many widely used geological reference materials.MethodsFor precise and accurate zinc isotopic ratio analysis of chemically diverse geostandards, including ultramafic to felsic igneous rocks, carbonatites, sediments and soils, an improved procedure for chemical purification of zinc was introduced in this study. The factors potentially affecting zinc isotopic ratio measurement were assessed. The accuracy and long‐term reproducibility were obtained by measurements on both synthetic solutions and well‐characterized geostandards.ResultsPurification of geologic samples with different zinc concentrations and matrix compositions yields consistent elution curves with nearly 100% recovery. Acidity and concentration mismatches and the presence of some matrix elements (e.g., Mg, Ti and Cr) have significant impacts on the precision and accuracy of zinc isotopic ratio measurement. The zinc isotope compositions of a suite of reference materials were measured using this method.ConclusionsThe present study describes methods for the chemical purification of zinc and high‐precision and accurate zinc isotopic ratio measurements using multicollector inductively coupled plasma mass spectrometer (MC‐ICP‐MS). The long‐term external reproducibility for δ66Zn values is ±0.04‰ (2SD). High‐quality zinc isotope data of chemically different geostandards were reported to stimulate future interlaboratory calibrations.

Mantle Oxidation Induced by Recycled Carbonate: Insights From Mg‐Zn‐Fe‐Cu Isotopic Systematics of Intraplate Basalts

“…The dissolved solutions were then loaded through a column filled with precleaned AG-MP-1M resin to separate Cu and Fe from other matrices (e.g., Ca, Ti, Na, and Mg), following the procedure outlined in . The same dissolved solutions were passed through an anion-exchange resin AG1-X8 for Zn purification (Liu, Li, et al, 2023). The same procedure was repeated once for Zn and Fe and twice for Cu to minimize matrix interference.…”

“…was measured in three blocks of 40 cycles and finally, the average and two standard errors of those values are reported (Table 1). The isotope data are reported in delta notation against reference Mg standard DSM-3 (Gao et al, 2019; Equation 1), Zn standard Lyon JMC 3-0749L (Liu, Li, et al, 2023; Equation 2), Fe standard IRMM-014 ; Equation 3), and Cu standard (SRM) NIST 976 Equation 4), respectively, expressed as…”

Determination of indium isotopic ratios of geostandards with different matrices by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS)

“…, Cu doping in Zn analyses), 11 and the technique can mitigate the effects of short-term fluctuations in the instrument mass bias and shows significant improvement of the analytical precision. 11–13 However, it is unclear whether elemental doping is applicable to In isotope analysis. The minimum In recovery during chemical separation is also unknown.…”