Slurry Nebulization Technique for Direct Determination of Rare Earth Elements in Silicate Rocks by Inductively Coupled Plasma Mass Spectrometry

Abstract

Direct analysis of silicate samples for the rare earth elements (REEs) by inductively coupled plasma mass spectrometry (ICP-MS) has been performed. Each finely ground sample (particle size <3μm) was dispersed in 0.1% aqueous Triton X-100 solution and nebulized into an inductively coupled plasma. The resulting ions were detected by mass spectrometry. Parameters such as particle size, slurry concentration and argon carrier flow rate exercised a great influence on sensitivity, precision and accuracy of slurry nebulization/ICP-MS. Calibration curves were constructed using aqueous standard solutions. The extended dynamic range (EDR) detection system allowed the use of matrix element as an internal standard; this procedure was effective to correct the differences in sensitivity between the solution and the slurry methods. The optimum procedure was applied to the determination of REEs in standard silicate rocks of the Geological Survey of Japan. The precision ranged from 0.8 to 6.3 (RSD, %) for REEs contents of 0.13-38ppm. Detection limits of REEs were excellent (0.002-0.02ppm at the effective integrating time of 10s).