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Research paper : Development and utilization of geochemical reference materials (T. OKAI)−72−Synthesiology - English edition Vol.9 No.2 (2016) interesting that during the 50 years of research and development, scenarios have been flexibly reviewed according to the user’s needs for reference materials, which have been reflected in the subsequent research plans. It is also noteworthy that the geological reference materials, including the ideas unique to Japan, are being used worldwide.This paper is structured in such a manner that it is easy to grasp for readers unfamiliar with this field, and will likely be used as a reference by many. I believe this is a paper well suited for publication in Synthesiology.Comment (Chikao Kurimoto, AIST)The Geological Survey of Japan (GSJ) and the Research Institute of Geology and Geoinformation of GSJ have published over 50 types of reliable reference materials during the past 50 years. The paper summarizes the significance, process, and results of studies by GSJ on the global trends in standard materials for geochemical reference and the development of these standard materials. In addition, the changes and future outlook of the standard materials with the advancement of analytical instruments have also been discussed. As such, this paper reviews the advances in geochemical reference materials in the last 50 years, and proposes future developments; and thus, I believe this paper is suitable for publication in Synthesiology.2 Importance of the wet methodQuestion (Akira Ono)Can I assume the following based on this paper? “The advantage of instrumental analysis is that it does not require labor and skills; however, analytical results are relative. Therefore, to calibrate the instruments, reference materials with absolute value for elemental concentration are necessary. In contrast, although the wet method requires labor and skills, its analytical results provide absolute value of elemental concentration. Therefore, the reference values of elemental concentration for reference materials are determined using the wet method.”If the above understanding is correct, in order to guarantee the reliability of analytical values (absolute value), the GSJ researchers also need to make technological advancement for the wet method to provide absolute value. What is your opinion on this issue? Is AIST still focusing on the wet method?Answer (Takashi Okai)In the early days of developing geochemical reference materials, values were determined using the wet method, as you have pointed out. However, now, as shown in Fig. 4, the values for silicon dioxide (SiO2) and ferrous oxide (FeO) are determined using the wet method (gravimetric method for SiO2 and titration method for FeO), and the values for other major components are obtained through general instrumental analyses, such as atomic absorption spectrometry and inductively coupled plasma atomic emission spectrometry. Studies have been conducted for the improvement of instruments and the assessment of the effect of other elements (such as interference). The precision of the quantitative analysis by these instrumental analyses has increased. With the adoption of official methods such as JIS, and the efforts of the NMIJ, the standard materials for each element have been prepared. The standard solution can now be prepared for the calibration curve with the certified reference materials for traceability. Furthermore, the values for standards are determined by collaborative analyses. However, sufficient precision in the wet method requires skills, and only a few institutions provide such skilled analyses.Currently, no new wet method is being developed for geochemical reference materials, but the wet method has been used for chemical analysis of geological samples for a long time, and there have been many improvements. Therefore, it is a well-AuthorTakashi OKAIGraduated from the Department of Chemistry, Faculty of Science, Tokyo University of Science in 1984. Joined the Geological Survey of Japan, Agency of Industrial Science and Technology (current AIST) in the same year. Currently leader of the Geochemistry Group, Research Institute of Geology and Geoinformation (Geological Survey of Japan). Ph.D. (Environmental Study, Graduate School of Environmental Studies, Nagoya University). An expert on analytical chemistry and geochemistry. Engaged in research of the chemical analysis for geological materials and in the geochemistry of carbonates. Currently engages in the preparation, chemical analysis and QC of geochemical reference materials. Awarded a Prize of the Minister of Education, Culture, Sports, Science and Technology (Department of Development) for the Development of Certified Geochemical Reference Materials in 2010.Preparation of new GSJ geochemical reference material Coral JCp-1, Geostandards Newsletter, 26, 95–99 (2002).[12]N. Imai, S. Terashima, S. Itoh and A. Ando: 1994 compilation of analytical data for minor and trace elements in seventeen GSJ geochemical reference samples, “Igneous rock series”, Geostandards Newsletter, 19, 135–213 (1995).[13]S. Terashima, M. Taniguchi, M. Mikoshiba and N. Imai: Preparation of two new GSJ geochemical reference materials: basalt JB-1b and coal fly ash JCFA-1, Geostandards Newsletter, 22, 113–117 (1998).[14]A. Ando: A new silicate rock standard, JG-1 issued from the Geological Survey of Japan, Geochemical Journal, 1, 155 (1967).[15]H. Kurasawa: A new silicate rock standard, JB-1 issued from the Geological Survey of Japan, Geochemical Journal, 2, 185 (1968).[16]A. Ando, H. Kurasawa, T. Ohmori and E. Takeda: 1971 compilation of data on rock standards JG-1 and JB-1 issued from the Geological Survey of Japan, Geochemical Journal, 5, 151–164 (1971).[17]A. Ando, H. Kurasawa, T. Ohmori and E. Takeda: 1974 compilation of data on the GSJ geochemical reference samples JG-1 granodiorite and JB-1 basalt, Geochemical Journal, 8, 175–192 (1974).[18]A. Ando, H. Kamioka, S. Terashima and S. Itoh: 1988 values for GSJ rock reference samples, “Igneous rock series”, Geochemical Journal, 23, 143–148 (1989).[19]T. Okai: GSJ certified geochemical reference materials, Chishitu News, 663, 61–63 (2009) (in Japanese).Discussions with Reviewers1 GeneralComment (Akira Ono, Special Emeritus Advisor AIST)The Geological Survey of Japan has been researching and developing geochemical reference materials for about 50 years. This paper clearly describes the scenarios of developing and providing geochemical reference materials in order to support highly reliable chemical analysis of geological samples. It is quite

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