Vol.5 No.4 2013

Research paper : Standardization of environmental analysis methods of hazardous chemicals (S. Taniyasu et al.)−279−Synthesiology - English edition Vol.5 No.4 (2013) Fig. 8 Result of the PFOS in river water sample for the ISO and JIS quality control testsNote) m = Average value of measurement, CVR = Reproducibility coefficient of variationproposed as the ISO standard in February 2005. At that time, there were hardly any reference standards for the individual isomers of NP, but since the necessity of isomer analysis was recognized worldwide through the establishment of ISO 24293, several branched-chain isomers including the 13C labeled standards are being sold by the reagent manufacturers today. Therefore, the improvement of reliability can be expected by using the commercially available standard materials in the next revision.4.2 Quality control study for PFOS/PFOABefore explaining the quality control performed in this research, the inter-laboratory study for the PFOS/PFOA-related substances conducted in early 2005 will be described. The inter-laboratory study was done using the in-house method (method that is not established as standard protocol) that each participant selected. The difference between the quality control study and the inter-laboratory study is that while the former is done for the purpose of assessing the analysis method and is conducted using a common SOP, the latter is done for the purpose of assessing the performance of laboratories on the analysis using in-house methods so there is no guideline for the analysis method used. The inter-laboratory study of 2005 was planned and managed by three organizations, Netherlands Institute for Fisheries Research, Örebro University, and Water Services Corporation. Thirty-seven international research institutes that have been working on the analysis technology development from the start of the PFOS problem, and five institutes from Japan (AIST, two companies, and two universities) participated. As a result, it was confirmed that the CVR surpassed 100 % for the variation of analysis value. The reasons indicated were the use of standards with low purity, contamination by sample containers, and errors due to the difference in sensitivity and calibration curve of the measurement devices. It became apparent that the mutual comparison of the analysis values obtained by the in-house method was difficult, and there was a need for standardizing the analysis method.[31] In this study, our group supplied the measurement data for PFBA with carbon number 4 for the first time in the world.The quality control study organized by AIST for checking the performance of ISO 25101 was done from November 2006 to February 2007 and 23 institutes from 9 countries participated. Since the quality control study was adopted to check the performance of the standard analysis method, the participants were required to use the draft of ISO 25101 as the SOP. The analyses were performed of river water, seawater, water containing low-concentration of the standard substance, water containing high-concentration of the standard substance, and the standard substance. The precision of CVR of 27 % or less was successfully obtained for each sample, where the concentration of PFOS in the actual sample was 2.6-470 ng/L and PFOA was 9.4-4400 ng/L (Fig. 8a). Similar quality control study was conducted for wastewater samples, but the CVR for PFOS reached 40 %, and the variation became greater than 30 % which was the guideline value set by ISO. Therefore, the wastewater sample was removed from the samples subjected to analysis in ISO 25101.After the establishment of ISO 25101, two quality control studies organized by AIST were conducted for JIS standardization, as requests were made by the Japanese laboratories for the compliance of the standard according to the principle of domestic standardization based on the international standard. In the first study conducted from March to July 2008, studies were conducted for tap water, seawater, river water, water containing low-concentration of the standard substance, water containing high-concentration of the standard substance, and the standard substance, using the same analysis method as ISO 25101. There were 13 participating institutes, and the study results were analyzed using the reports submitted by 11 institutes. In most samples, good results were obtained where CVR of PFOS/PFOA and their related substances was within 30 % (Fig. 8b), and it was confirmed that ISO 25101 could be used in the Japanese analytical laboratories. However, some points had to be reviewed, such as, the variation of the study results for low-concentration water samples and the low recovery rate of long-chain compounds. In the second quality control study conducted from September 2009 to January 2010, the industrial water and plant wastewater were used as the main subjects of measurement for the JIS standardization. There Lab no.Lab no.Lab no.PFOS concentration (ng/L)c) Second JIS quality control study resultb) First JIS quality control study resulta) ISO quality control study result11923311422226141724250426810412117813140246812252617103529213209051015= 27 %= 6.63 ng/L,Rm CVR= 20 %=3.26 ng/L,m CV= 27 %= 9.1 ng/L,Rm CV


page 55