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Research paper : Standardization of environmental analysis methods of hazardous chemicals (S. Taniyasu et al.)−280−Synthesiology - English edition Vol.5 No.4 (2013) were 30 participating institutes, and the analyses of the study results were done for the reports submitted by 23 institutes. In this study, satisfactory results (CVR < 30 %) were obtained for all samples of PFOS/PFOA (Fig. 8c). It can be thought that the analysis error due to the difference in the in-house method was controlled by using the SOP, including the reference standard for creating the calibration curve.5 Feedback for the effort on the international regulation of hazardous chemical substances using the ISO standardHow are these international standards being utilized?First, for ISO 24293, the necessity of individual NP isomer analysis was recognized internationally, and the sales of reference standards for individual isomers were started by reagent manufacturers. Germany added the measurement for individual isomers when standardizing ISO 18857-2[32] (analysis method for alkylphenols including NP using the solid phase extraction method and the derivatization method) that is the second part of ISO 18857-1[9] (analysis method for alkylphenols including NP using the liquid-liquid extraction method; NP is the total measurement).As an example of the use of ISO 25101, Company S, which is a Japanese manufacturer of semiconductors and assembled products, requested AIST to assess the environmental load and the percentage of PFOS in the chemicals used in their plants from 2003. Company S took measures against the PFOS issue before other companies and regulations were implemented. It obtained the information on the amount of PFOS used and the environmental load in 2006, and shifted to alternative substances, and sufficient safety measures were achieved by the time interviews and surveys were conducted by METI in 2008. On the other hand, the companies that did not take measures against PFOS by 2009 had to struggle to take action in a short period, as they had to determine the usage amount and shift to alternative substances while facing the countdown for regulations. If this was done by a private analytical laboratory without strict quality control, there might have been questions about the reliability of the values reported. The survey results in compliance with the ISO 25101 were readily accepted, and this helped the consideration of the exceptions and essential use according to the Chemical Substances Evaluation Act.In the analysis, a reference material that has been accurately characterized is necessary to determine the measurement value. Previously, there was no choice but using the values provided by the chemical suppliers, but the National Metrology Institute of Japan (NMIJ), AIST, developed the certified reference material (CRM)Term 6 appropriate for ISO 25101 that is traceable to the SI . To strengthen the linkage of the reference material and the standards inside and outside Japan as much as possible, the development of the reference material was performed concurrently with the international standardization for PFOS, and as a result, quick provision was possible for the CRM related to PFOS. For the development of CRM, NMIJ conducts a management system in compliance to the ISO Guide 34[33] and ISO/IEC 17025[34] which are the guidelines for the production of reference materials, and our CRM is produced accordingly. To ensure the traceability to the SI, the application of the primary method of measurementTerm 7 [35] is recommended. The freezing point depression method, one of the primary methods, is often chosen in the purity assessment of the organic reference materials. However, since the raw material used was potassium salt of PFOS (K-PFOS) that could be readily refined, the melting point was extremely high (about 300 °C), and it was difficult to obtain accurate results using the purity assessment by the freezing point depression method[36]-[39] (about 150 °C or less) developed by NMIJ. The reproducibility of measurement was improved by using the high- pressure sample crucibles and by applying the reference material for the high-temperature melting point calibration to the freezing point depression method. Hence, it was possible to determine the purity traceable to the SI for the high melting point material such as the K-PFOS (Fig. 9). Therefore, it is expected that the purity assessment of many hazardous materials will become possible by combining this method with the conventional method.[40] The preparation of solution of this reference material was applied to the NIST SRMNIST SRMmol/molDifferential scanning calorimeterkg/kgkgWeights calibrated by JCSSBalanceCoulometric Karl Fischer titratorWater content analysisAnalysis of amount-of-substance fraction of impuritiesNMIJ CRM 4220‐aCharacterization by freezing point depression methodFig. 9 Traceability diagram of potassium perfluorooctanesulfonate in methanol (NMIJ CRM 4220-a)Note) JCSS = Japan Calibration Service System; NIST SRM = Standard Reference Material from the National Institute of Standards and Technology (USA).

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