Improved Nd chemical separation technique for ¹⁴³Nd/¹⁴⁴Nd analysis in geological samples using packed Ln resin columns

Abstract

For the measurement of ¹⁴³Nd/¹⁴⁴Nd ratios, Nd must be separated from the major matrix and isobaric interfering elements before mass spectrometry measurements are performed. We report an improved technique for the separation of Nd from the other rare earth elements (REE), in particular Ce and Sm, in geological samples. This method uses Ln resin chromatography, combining oxidative and conventional “Ln-resin” procedures in order to remove Ce and Sm, respectively, from the Nd fraction. Repeated analyses of ¹⁴³Nd/¹⁴⁴Nd in standard JNdi-1 prepared using the newly developed technique are in good agreement with the values measured by direct analysis. The procedural Nd blanks are extremely small. The recovery yield of Nd after the entire separation process was always better than 90%, which is better than the recovery realized in previous studies owing to the collection of wider Nd elution points by the effective removal of neighbour elution elements (Ce and Sm). The ¹⁴³Nd/¹⁴⁴Nd ratios of four igneous rock reference materials (JB-1a, JB-2, JA-1, JR-1) were also analysed, and the mean values were consistent with those given in previous reports, indicating the reliability of our new Nd separation chromatography technique.