Issue 9, 2022

In situ measurement of Sm–Nd isotopic ratios in geological materials with Nd < 100 μg g−1 by LA-MC-ICP-MS

Abstract

In this study, we developed a method for measuring Sm–Nd isotopic ratios in samples with low Nd contents (<100 μg g−1) by LA-MC-ICP-MS. The use of jet sample and X skimmer cones, with the addition of a small water vapour flow (∼5 mL min−1) significantly improved the instrumental sensitivity by a factor of 1.9–3.6, and has little effect on Nd instrumental mass bias. The accuracy and precision of our analytical method is demonstrated by analysis of eight geological reference glasses (Nd = 21.4–60.9 μg g−1). The obtained Sm–Nd isotope data are consistent with their recommended values. The measurement of a clinopyroxene megacryst (JLM-1) indicates that matrix effects on 147Sm/144Nd calibration between clinopyroxene and the measured geological reference glasses are insignificant. The inverse correlation between the analytical precision and the Nd signal intensity shows that the 143Nd/144Nd internal precision is <120 ppm (2s) for a 146Nd signal >0.15 V, whereas the 143Nd/144Nd internal precision is <80 ppm (2s) for a 146Nd signal >0.3 V. The addition of water vapour did not suppress the matrix effects for 147Sm/144Nd calibration. The Sm–Nd isotopic compositions of the Panzhihua clinopyroxene measured with our method indicate that the Panzhihua layered intrusion behaved as a closed magmatic system that experienced limited crustal contamination. The method presented in this study is a rapid and accurate technique for in situ analysis of Sm–Nd isotopes of low-Nd samples, such as volcanic glass, clinopyroxene and hornblende.

Graphical abstract: In situ measurement of Sm–Nd isotopic ratios in geological materials with Nd < 100 μg g−1 by LA-MC-ICP-MS

Supplementary files

Article information

Article type
Technical Note
Submitted
26 máj 2022
Accepted
20 júl 2022
First published
27 júl 2022

J. Anal. At. Spectrom., 2022,37, 1776-1786

In situ measurement of Sm–Nd isotopic ratios in geological materials with Nd < 100 μg g−1 by LA-MC-ICP-MS

L. Zhang, F. Yang, L. Hong, Y. Zhang, J. Soldner, Y. Zhang and Z. Ren, J. Anal. At. Spectrom., 2022, 37, 1776 DOI: 10.1039/D2JA00181K

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