ABSTRACT

The concentrations of fourteen rare earth elements (REEs) in GSJ/AIST geochemical reference materials JCp-1 (coral) and JCt-1 (giant clam) were identified by isotope dilution inductively-coupled plasma-mass spectrometry, using a quadrupole mass filter (ID-ICP-QMS). Large samples (2~4.1 g) were used to eliminate inhomogeneities in the sample powders. The sample powders were spiked with enriched isotopes and decomposed using HCl. The REEs were separated from the matrix elements by Fe(OH)₃-coprecipitation and purified by cation-exchange chromatography. The REEs were further divided into light REE, middle REE, and heavy REE fractions using cation-exchange chromatography, eluted with 2-hydroxyisobutyric acid (HIBA). The abundances for ten poly-isotopic REEs were obtained using both the isotope dilution method and the conventional peak height comparison method, using a calibration curve. The recovery rates for the ten REEs were then calculated by comparing the values obtained by these two methods. The obtained recovery rates were then interpolated for mono-isotopic REEs, and their concentrations were corrected from their relative peak heights. The obtained values were determined twice, using different spike/sample ratios, and agreed within +/–2%, with the exception of La, Ce, and Ho. The ID gave precise abundances for the fourteen different REEs rapidly and easily.