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 <3 µm) 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 -38 ppm. Detection limits of REEs were excellent (0.002 -0.02 ppm at the effective integrating time of 10 s). KeywordsSlurry nebulization, inductively elements coupled plasma mass spectrometry, silicate analysis, rare earthInductively coupled plasma (ICP) is now becoming accepted as an effective ionization source for subsequent mass spectrometric measurement. Comprehensive reviews have been presented by Date', Houk2 and Kawaguchi.3 In initial works on ICP mass spectrometry (ICP-MS), samples were generally introduced into ICP as aerosols of aqueous solutions; therefore, the dissolution of solid samples was required for many applications. This process is quite labor-intensive and time-consuming, especially for the analysis of refractory ceramic or silicate rocks.

Slurry nebulisation ICP-MS direct determination of high field strength elements (Nb, Ta, Zr, and Hf) in silicate rocks

“…[35][36][37][38][39] The slurry nebulisation technique offers unique advantages over other types of solid sample introduction methods such as laser ablation (LA) 40 or electrothermal evaporation (ETV) 41 because it has the potential for calibration with aqueous standards, together with essentially a conventional pneumatic sample introduction system. 42 Although ICP-MS typically presents a three-order of magnitude sensitivity and simple spectra better than those from ICP-OES, there are few reports [43][44][45] in the literature of slurry nebulisation in ICP-MS, probably due to its low intolerance for matrix effects owing to particle deposition on the sampler cone, and the consequent need to dilute that impairs the detection capability. 46 Only one study based on the slurry nebulisation ICP-MS technique to analyse Nb and Ta in 13 geological certi-ed reference materials (CRMs) was found.…”

“…However, previous studies by ICP-OES on the direct analysis of slurries indicated there is a limitation associated with the use of solution standards. 47,48 Compared to the signal response of Cr and Ni obtained by solution nebulisation in plasma during the ICP technique, only 30-50% of the signal response of Cr and Ni was obtained by slurry nebulisation with a particle size of 6 mm. 47 Mochizuki et al 48 observed that the relative signal responses (RSRs) of rare earth elements were improved up to 61-83% when a smaller particle size of 3 mm was adopted.…”

“…47,48 Compared to the signal response of Cr and Ni obtained by solution nebulisation in plasma during the ICP technique, only 30-50% of the signal response of Cr and Ni was obtained by slurry nebulisation with a particle size of 6 mm. 47 Mochizuki et al 48 observed that the relative signal responses (RSRs) of rare earth elements were improved up to 61-83% when a smaller particle size of 3 mm was adopted. Although long milling times (>8 h) were required to obtain the desired particle size range (3 to 6 mm), an obvious trend of increases in the RSR with decreases in the particle size was observed.…”

“…Although long milling times (>8 h) were required to obtain the desired particle size range (3 to 6 mm), an obvious trend of increases in the RSR with decreases in the particle size was observed. 48 Therefore, a value of the RSR close to 100% is a good prerequisite for the direct use of simple aqueous standards to calibrate the slurry introduction technique. The aim of this study was to develop a reliable slurry nebulisation ICP-MS method that can be used to obtain accurate data on the content of HFSEs in silicate rocks.…”

Analysis of rice and wheat flour by particle nebulization ICP-MS

“…25 Compared with the LA sampling technique, the advantage of slurry nebulization is that it has the potential for direct calibrations with conventional aqueous standards using a solution nebulization introduction system. 26 Some applications of slurry nebulization ICPoptical emission spectrometry (ICP-OES) technique for the analysis of the geological and inorganic material samples are reported; [27][28][29][30][31][32][33][34] however, the matrix effects in ICP-MS are much more serious than the ICP-OES technique. Recently, we have tried to use the slurry nebulization ICP-MS technique to measure the high eld strength elements (Nb, Ta, Zr, and Hf) in silicate rocks.…”