日本地球惑星科学連合2019年大会

講演情報

[J] ポスター発表

セッション記号 S (固体地球科学) » S-GC 固体地球化学

[S-GC41] 固体地球化学・惑星化学

2019年5月29日(水) 15:30 〜 17:00 ポスター会場 (幕張メッセ国際展示場 8ホール)

コンビーナ:下田 玄(産業技術総合研究所地質調査総合センター)、鈴木 勝彦(国立研究開発法人海洋研究開発機構・海底資源研究開発センター)、山下 勝行(岡山大学大学院自然科学研究科)、石川 晃(東京工業大学理学院地球惑星科学系)

[SGC41-P08] fsLA-ICPMS analysis of XRF glass beads

*常 青1佐藤 智紀2木村 純一1 (1.国立研究開発法人・海洋研究開発機構・地球内部物質循環研究分野、2.国立研究開発法人・海洋研究開発機構・海洋掘削科学研究開発センター)

キーワード: femto-second LA-ICP-MS、bulk analysis、XRF glass bead、 geological reference materials

Analysis of naturally heterogeneous rock samples by ICP-MS requires laborious sample preparation including acid/alkali digestion. Crystalline plutonic rocks or sediments remains as challenging analysis by ICP-MS because of the difficulty in complete digestion of acid resistant minerals which contain significant fraction of high field strength elements (HFSE) or rare earth elements (REE). We tested femto-second laser ablation (fsLA) ICP-MS analysis of glass beads prepared for X-ray fluorescence spectrometry (XRF). This method maintains benefits of no sample digestion by wet chemistry, high sensitivity, high sample throughput and low costs. A comprehensive examination of measurement parameters was made on wave length and repetition rate of the laser beam. Choice of internal standard and external calibration method were also examined. Using high-diluted glass beads (1:10 sample to lithium tetraborate ratio) and optimized in-house developed fsLA system coupled to a quadruple-type ICP-MS (iCAP Qs, ThermoFisher Sci.), the parameters and methods were validated by determining 48 elements including ten major (Si, Ti, Al, Fe, Mn, Mg, Ca, Na, K, P), refractory lithophile (Sr, Ba, REE and HFSE) and volatile (Ga, Rb, Cs, Tl, Pb) elements in well-established geological reference materials (GSJ JB-1, JG-1a, JG-2 and JR-1) and synthetic reference glasses (NIST SRM 612, USGS GSD-1G). Laboratory bias (or trueness by ISO 5725-1) for most elements was better than 10% when compared to the reference or consensus values. Poorly determined or failed elements were P, Sc, V, Ni, Sn, Sb, and W, whose data deviated from the reference values >20%. Volatile elements such as Rb, Cs and Ga showed no substantial loss; however, Tl and Pb exhibited always lower values suggesting their loss during fusion in the glass bead preparation. Repeatability and intermediate precision (ISO 5725-1) of all measured elements were better than 5–7% RSD except Cu, Sn, Sb, Cs and Tl which showed 10–40% RSD due to extremely low abundances or strong spectral interferences. The low limits of detection by this method were comparable to those obtained by solution ICP-MS for most elements of geochemical interests. Our results demonstrate that the fsLA-ICPMS using XRF glass bead can be used for rapid bulk-rock analyses of trace, minor and major elements.