Comparison of PGAA and wet chemical analysis for determining major element contents in eucritic meteorites

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Comparison of PGAA and wet chemical analysis for determining major element contents in eucritic meteorites N. Shirai1   · T. Hozumi1 · Y. Toh2 · M. Ebihara1,3 Received: 13 April 2020 © Akadémiai Kiadó, Budapest, Hungary 2020

Abstract Prompt gamma-ray activation analysis (PGAA) was applied to well homogenized meteorite samples initially prepared for the wet chemical analysis. By comparing the PGAA data with wet chemical analysis data in literatures, it was confirmed that PGAA can be alternative or even advantageous to wet chemical analysis in terms of the data reliability. Because the same sample can be analyzed by INAA followed by PGAA, data obtained by a combination of PGAA and INAA were proved to enable us to discuss the detailed chemical characteristics of meteorite samples represented by eucritic meteorites (eucrites). Keywords  Prompt gamma-ray activation analysis (PGAA) · Instrumental neutron activation analysis (INAA) · Wet chemical analysis · Eucrites · Meteorites

Introduction In 1969, nine meteorites were accidentally found on Antarctica by the Japanese Antarctic expedition team. Since then, about 50,000 meteorites have been collected from Antarctica so far. Meteorites are precious materials from which the formation and early differentiation of our solar system can be elucidated. Antarctic meteorites cannot be personal properties, but are shared by the public. When those samples are needed for scientific purposes, users are to submit sample requests to appropriate agencies such as the National Institute of Polar Research (NIPR), Tokyo, Japan. For such processing, the agencies are required to supply sufficient information regarding meteoritic materials. As for such information, classification is the most fundamental and important. Meteorites are classified based on several characteristics such as petrological and mineralogical features,

* N. Shirai shirai‑[email protected] 1



Department of Chemistry, Tokyo Metropolitan University, 1‑1 Minami‑Osawa, Hachioji, Tokyo 192‑0397, Japan

2



Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Shirakata, Tokai‑mura, Ibaraki 319‑1195, Japan

3

Department of Earth Sciences, Waseda University, 1‑6‑1 Nishi‑Waseda, Shinjuku‑ku, Tokyo 169‑8050, Japan



elemental compositions and isotopic abundances. Among them, major element compositions can be key information. In order to determine major element contents, so-called wet chemical analysis has been extensively used for many years [1, 2]. A major advantage of this method is being capable of determining almost all major elements. In addition, for iron, individual values of different chemical states (­ Fe0+, ­Fe2+ and ­Fe3+) can be separately determined. For ­H2O, ­H2O (+) (constitution water) and ­H2O (−) (absorbed water) can be also separately determined. Disadvantages of this method are that the samples need to be physically destroyed and that gram-sized mass of the individual samples are consumed. Considering that some meteorite specimens are in such sizes, the wet chemical analysis cannot be a pr