Single Column REE Separation and Radiogenic ¹⁴³Nd/¹⁴⁴Nd Analysis Without Sm Elimination

Abstract

A single column separation method has been developed for the determination of radiogenic 143Nd/144Nd ratios for natural geological samples. Conventional radiogenic Nd isotope ratio measurements require rigorous column chemistry involving multiple steps to extract a pure Nd fraction. Elements that cause isobaric interference during analysis are removed using a multi-column separation method, which is often time consuming and/or expensive. In this work, we use a single cation exchange column to extract a Nd fraction, and a novel method of mass fractionation correction to circumvent the isobaric effect of Sm during analysis. The developed method allows accurate measurement of the 143Nd/144Nd ratio without the elimination of Sm. The ratio of two non-radiogenic Nd isotopes with no natural isobars, 145Nd/146Nd, is used to correct for instrumental mass fractionation on 143Nd/146Nd. The corrected 143Nd/146Nd ratios can be converted to the 143Nd/144Nd form using the conventionally used constant ratio of 146Nd/144Nd of 0.721900, allowing direct comparison with published literature and databases. We have implemented this sample preparation scheme to generate accurate and precise radiogenic 143Nd/144Nd ratios for nine natural reference materials including basalts, granites, sediments and sedimentary rocks, confirming the applicability and robustness of this technique.