A rapid single column separation scheme for high-precision Sr–Nd–Pb isotopic analysis in geological samples using thermal ionization mass spectrometry

Abstract

Thermal ionization mass spectrometry (TIMS) is considered the most accurate technique for determining Sr–Nd–Pb isotopic ratios in geological samples. However, time-consuming and complex sample separation procedures greatly hinder the instrumental measurement efficiency. In this study, a single-column separation chemistry procedure for Sr–Nd–Pb from single rock dissolution was developed. The chemistry procedure was designed to minimize the number of evaporation steps and considerably shorten the separation time, enabling high throughput for TIMS. In contrast to conventional three-column separation procedures (∼3 days), this technique was characterized by high efficiency superiority in terms of separation time (∼8 hours), a 3-fold enhancement in the separation efficiency. The stability of our procedure was demonstrated by replicated TIMS measurements of ⁸⁷Sr/⁸⁶Sr, ¹⁴³Nd/¹⁴⁴Nd, ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb ratios for six international silicate rock reference materials, spanning a wide range of bulk compositions. The analytical results obtained for these standards agreed well with published data. The external reproducibility (2 RSD, n = 10) of a BCR-2 standard sample was ±0.0020% for ⁸⁷Sr/⁸⁶Sr, ±0.0023% for ¹⁴³Nd/¹⁴⁴Nd, and ±0.021–0.033% for ²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb ratios.