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Research paper : Development and utilization of geochemical reference materials (T. OKAI)−71−Synthesiology - English edition Vol.9 No.2 (2016) the needs of environmental and morphological analysis will be desired. The largest problem with the development of such reference materials is the stability of the sample. This paper did not address stability, which is an important factor for reference materials. The reason for this omission is that rock samples are fundamentally stable and can be used almost indefinitely. JG-1 and JB-1 samples can still be used as reference materials from data analyzed more than 40 years ago. However, for samples suitable for environmental and morphological analysis, even if suitable reference materials were developed, the duration of their usage would be highly limited. For example, for the analysis of hexavalent chromium in contaminated soil samples (includes certain organics and water), much of hexavalent chromium would change to trivalent chromium after a certain period of time after grinding and packaging in a bottle. Thus, even if reference materials for analysis of hexavalent chromium could be prepared, their effective duration would be extremely short. In addition, the matrix of reference materials that will be demanded in environmental analysis is diverse, and the target components will also likely be diverse. Hence, in order to perform accurate analysis with the automatic analysis methods described earlier, it is necessary to develop reference materials suitable to this more diverse matrix in the shortest amount of time possible. The GSJ reference materials are prepared by grinding natural samples, and at least several years are required from conceptualization of development to supply. Hence, as the supply needed in the future would be impossible with such a short cycle and timeframe, the development of reference materials for which the necessary matrix and components are industrially synthesized is desired. It will be difficult to respond to this need by GSJ alone, and this technological development is extremely important not only for geochemistry but also for overall reference materials. Therefore, with the leadership of the National Metrology Institute of Japan (NMIJ), knowledge and technology in each area of the National Institute of Advanced Industrial Science and Technology (AIST) should be combined to more effectively address this issue.5.3 Future plans for GSJ geochemical reference materialsThe importance of the currently prepared geochemical reference materials will not change in the future. As mentioned earlier, because these references can be used indefinitely, mutual evaluation of analytical results 40 or more years old and current results is possible, and their supply as foundational reference materials needs to be maintained. Currently, samples prepared in the initial series are being exhausted; thus, there is a focused effort on re-preparation of samples in order to maintain the supply of reference materials. In addition, through recent research developments, elemental analyses of individual trace minerals that constitute the boundary of minerals are being attempted through localized analysis using lasers and ion probes. Reference materials vitrified by the melting of rocks (homogenized through vitrification) that can respond to such localized analysis are desired. Currently, only the USGS is able to provide the reference materials vitrified through the melting of rocks. It is necessary to closely examine this topic, including cooperation with the USGS.Finally, in the development of reference materials, the most important concern in any situation is to maintain analytical technology that can provide accurate values (standard values). In the future, a variety of reference materials will be prepared, but the necessity of assigning an accurate value will not change. As mentioned earlier, as the number of experienced technicians decreases and the number of technicians who work as operators of instrumental analysis equipment increases, this is the most important issue for GSJ and AIST as research organizations that represent the nation.AcknowledgmentsDr. Noboru Imai of the Research Institute of Geology and Geoinformation provided valuable documents along with much advice that were helpful for the writing of this paper. I extend my thanks and respect to Dr. Imai and all predecessors associated with geochemical reference materials.References[1]A. Ando: Geochemical standards, Chishitu News, 158, 23–27 (1967) (in Japanese).[2]H. W. Fairbairn and others: A cooperative investigation of precision and accuracy in chemical, spectrochemical and model analysis of silicate rocks, U. S. Geological Survey Bulletin, 980, 1–71 (1951).[3]R.E. Stevens, M. Fleischer, W.W. Niles, A. A. Chodos, R. H. Filby, R. K. Leininger, L. H. Ahrens and F. J. Flanagan: Second report on a cooperative investigation of the composition of two silicate rocks, U. S. Geological Survey Bulletin, 1113, 126 (1960).[4]M. Fleischer and R.E. Stevens: Summary of new data on rock samples G-l and W-l, Geochimica et Cosmochimica Acta, 26, 525–543 (1962).[5]C.O. Ingamells and N.H. Suhr: Chemical and spectrochemical analysis of standard silicate samples, Geochimica et Cosmochimica Acta, 27 (8), 897–910 (1963).[6]A. Ando: Processing of reference rock powders, Bunseki, 116, 597–602 (1984) (in Japanese).[7]S. Iizuka and K. Inami: Measurements of physical properties for geochemical rock standards GSJ JG-1 and JB-1, Bull. Geol. Surv. Japan, 27, 155–165 (1976) (in Japanese).[8]The Association for the Geological Collaboration in Japan ed.: New Cyclopedia of Earth Sciences, appended figures and tables, Heibonsha Ltd., Tokyo, 71 (1996).[9]S. Abbey: Studies in “standard samples” for use in the general analysis of silicate rocks and minerals, Geological Survey of Canada Paper, 77–34 (1977).[10]P. J. Potts, A. G. Tindle and P. C. Webb: Geochemical Reference Material Compositions, Whittles Publishing, London, (1992).[11]T. Okai, A. Suzuki, H. Kawahata, S. Terashima and N. Imai:

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