Liu Sheng-Ao, Li Dandan, Liu Wan, Wu Tianhao, Yang Chun
State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing, China.
State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China.
Rapid Commun Mass Spectrom. 2023 Sep 15;37(17):e9606. doi: 10.1002/rcm.9606.
Zinc 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.
For 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.
Purification 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.
The 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 δ Zn values is ±0.04‰ (2SD). High-quality zinc isotope data of chemically different geostandards were reported to stimulate future interlaboratory calibrations.
锌同位素在高温地球化学中的应用越来越广泛，例如在地壳 - 地幔相互作用和与挥发作用相关的过程中。然而，一些常用参考物质已发表的锌同位素数据显示出较大的实验室间偏差。此外，许多广泛使用的地质参考物质的锌同位素组成数据仍然有限。
本研究针对包括超镁铁质到长英质火成岩、碳酸盐岩、沉积物和土壤等化学性质多样的地质标准物质，引入了一种改进的锌化学纯化程序，用于精确准确的锌同位素比值分析。评估了可能影响锌同位素比值测量的因素。通过对合成溶液和特征明确的地质标准物质进行测量，获得了准确性和长期重现性。
对不同锌浓度和基质组成的地质样品进行纯化，得到了一致的洗脱曲线，回收率接近100%。酸度和浓度不匹配以及某些基质元素（如Mg、Ti和Cr）的存在对锌同位素比值测量的精密度和准确性有显著影响。使用该方法测量了一组参考物质的锌同位素组成。
本研究描述了锌的化学纯化方法以及使用多接收电感耦合等离子体质谱仪（MC-ICP-MS）进行高精度准确的锌同位素比值测量。δZn值的长期外部重现性为±0.04‰（2SD）。报告了化学性质不同的地质标准物质的高质量锌同位素数据，以促进未来的实验室间校准。
