Certified calibration solution reference material for the determination of perfluorooctane sulfonate from the National Metrology Institute of Japan (NMIJ)

• Published in: International journal of environmental analytical chemistry Vol. 93; no. 6; pp. 692 - 705
• Main Authors: Hanari, Nobuyasu, Itoh, Nobuyasu, Ishikawa, Keiichiro, Iwasawa, Ryoko, Aoyagi, Yoshie, Yarita, Takashi, Numata, Masahiko
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 01.05.2013; Taylor & Francis LLC
• Subjects: Analytical chemistry; Calibration; calibration solution reference material; Chemical compounds; confidence interval; coulometric Karl-Fischer water content titrator (KFT); differential scanning calorimeter (DSC); freezing point; methanol; metrology; mixing; molecular weight; perfluorooctane sulfonate anion (PFOS); potassium; potassium perfluorooctane sulfonate (K-PFOS); Raw materials; Research centers; salts; Uncertainty; Japan
• ISSN: 1029-0397; 0306-7319; 1029-0397
• DOI: 10.1080/03067319.2012.684048

A new calibration solution reference material for the determination of perfluorooctane sulfonate anion (PFOS) and its salts has been issued as a certified reference material (CRM) by the National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ/AIST). The purity amount-of-substance fraction of raw material potassium perfluorooctane sulfonate (K-PFOS) was evaluated based on the results obtained using the freezing point depression method, and the purity mass fraction of the raw material was calculated using the average molar mass of impurities, the molar mass of K-PFOS, and the purity amount-of-substance fraction. The certified concentration of this CRM was obtained by multiplying the dilution ratio of the raw material in a prepared solution (methanol) determined from the gravimetric blending method by the purity of the raw material. The preparation concentration of K-PFOS as a certified value of NMIJ CRM 4220-a was determined to be 9.93 mg kg⁻¹. In addition, the standard uncertainty of the certified value was evaluated from the purity evaluation as well as from sample inhomogeneity, instability, and preparation variation obtained from LC/MS measurements of different gravimetrically prepared solutions of the NMIJ CRM. Consequently, the expanded uncertainty was estimated to be 0.15 mg kg⁻¹ with a coverage factor k = 2 corresponding to the half-width of estimated confidence interval of approximately 95%.