Vol.9 No.2 2016

Research paper : Development and utilization of geochemical reference materials (T. OKAI)−73−Synthesiology - English edition Vol.9 No.2 (2016) developed method. In the wet method, expertise, which is difficult to express in the procedure of an analytical method, can lead to differences. AIST has abundant expertise and is focusing on maintaining the technology for accurate wet method analysis. Specifically, in addition to passing on the skills to the younger generations, given the current situation where there are few institutions that are able to perform the wet method analysis, it would be important to share the information externally in order to sustain the use of the technology.3 Relationship where the analytical methods and target materials compete in terms of accuracyComment (Akira Ono)I thought it was interesting that in the early stages of development of the geochemical reference materials described in Subchapter 2.2, when common samples were collaboratively analyzed by major institutions around the world, the variability in data was much larger than expected. As a result, it led to a higher precision of the analytical method. The reviewer has the following proposition on this issue. What is the authors’ opinion?Analysis consists of methods and target materials. If a certain target material is analyzed with multiple analytical methods and the results vary, there are two possible causes for such variability. One is the variability existing in the analytical methods, including the reproducibility of the measurements. The other is the variability existing in the target material itself, which can be attributed to the heterogeneity in a sample or temporal changes in its characteristics. These two types of variability are observed together, and usually cannot be separated. However, if one type of variability is assumed to be significantly less than the other, the more significant cause for the variability can be clearly identified, and a clear way to reduce such variability can thus be conceived.As discussed in Subchapter 2.2, the cause of variability in the analytical results could not be attributed to the variability of the targets, but was because of the variability of the analytical methods. This inference led to the beginning of new studies.In contrast, to evaluate the variability of target materials, a much more stable analytical method must be used. We assume that instrumental analysis has a better resolution and stability compared to the wet method. As such, the analytical method and target compete with each other as far as accuracy is concerned. If one makes progress, the other follows until it surpasses its counterpart. In this manner, both make progress. The present case was an example of such a situation, which I found interesting.I also feel that those taking part in the collaborative analysis without fear of varying results in a stage where the results were unpredictable (not being afraid of his/her own result being different from others) are worthy of praise for their courage and determination. This effort is considered to be of universal value till date.Answer (Takashi Okai) Regarding the variability of the results, I was amazed by the high technological level back then. In a collaborative analysis, when evaluating the variability of analytical methods and target materials that you commented on, little variation in the skills of the participating analysts needs to be ensured. When multiple analysts perform the same analytical method, if there is variability of analytical skills (or if overall skill level is low), the results will show variability beyond the fundamental variability expected in that analytical method. In such a case, if multiple analytical methods are compared, the variability of each analytical method becomes larger than the variability between the analytical methods, and the difference between each analytical method is masked. In the present study, the difference observed for silicon dioxide, as shown in Fig. 2, was due to a few procedure differences in the gravimetric methods rather than differences in the analytical methods. For such a minor difference in procedure to be identified as a difference caused by the analytical methods, each analyst had to have performed their analyses with extremely high precision. Therefore, it reaffirmed the extremely high level of analytical skills exhibited by institutions that took part in the collaborative study back then. The competition between the analytical methods and the target materials was also inferred. In the response to discussion 2, I stated that these days the values for standard materials are mainly determined through instrumental analysis. Indeed, the development in instrumental analysis and standard materials impacted on each other, and in both cases, progress was made owing to the competition.Participating in a collaborative study is a serious challenge; however, I think that pride as a skilled analyst was an important motivation (the possibility that one’s own data may be the only outlier can put great pressure on an analyst). I believe it is important to guide the next generation until they attain such pride as analysts.4 Underlying technologies and strengths of GSJComment (Chikao Kurimoto)In Section 3.1.3, the elemental technologies and strengths of GSJ have been discussed. Figure 3 shows their relationship. The content is correct, but if Fig. 3 could illustrate the relationship of the two and their impacts, their relationship would become clearer. It could clearly indicate the significance of this study and the elemental technologies and strengths of GSJ.Answer (Takashi Okai)As you have pointed out, the elemental technologies and strengths of GSJ have merely been listed. Therefore, along with the content of Section 3.1.3, I have inserted the impacts of strengths of GSJ on the examination of the elemental technologies between the two, and have connected these relationships using arrows. Thus, the findings of our study and the elemental technologies and strengths of GSJ were integrated.5 GSJ geochemical reference materials Comment (Chikao Kurimoto)Subchapter 5.3, titled “Future plans for GSJ geochemical reference materials,” is quite interesting. This paper summarizes the long-term progress in geochemical reference materials, which is a valuable indication of the future prospects. Therefore, comments on the fundamental policy and future plans of GSJ would have been beneficial for the readers. In future, I hope that there will be further discussions within GSJ based on this paper. Answer (Takashi Okai)At present, these are simply ideas that I have, and hence, I refer to them as “future plans.” However, I hope to utilize them for future discussions.


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