title: Variation in concentration of perfluorooctanoic acid in methanol solutions during storage.
abstract: Perfluoroalkyl carboxylic acids (PFCAs) including perfluorooctanoic acid (PFOA) have been widely recognized as persistent environmental contaminants. For accurate quantification of PFCAs, their stability in calibration solutions is important because they are criteria of quantification. To examine stability of PFCAs in methanol, we monitored PFOA and its related compounds around 4 years. Interestingly, perfluorooctanoate was varied randomly, and methyl perfluorooctanoate (MePFOA) and methyl formate were observed when perfluorooctanoate decreased. Moreover, no detection of both methyl esters was in methanol solutions immediately after preparation. In each of prepared methanol solution of perfluorohexanoic, perfluoroheptanoic, and perfluorononanoic acids, their corresponding methyl esters and methyl formate were observed. Furthermore, MePFOA was observed even in the solutions stored around 4 months and thereafter MePFOA increased with increase in methyl formate. Therefore, PFCAs including PFOA should be used immediately after preparation when methanol is used as a solvent.
authors.affiliation: National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ/AIST), 1-1-1, Umezono, Tsukuba, Ibaraki 305 8563, Japan. Electronic address: hanari-n@aist.go.jp.
authors.forename: Nobuyasu
authors.initials: N
authors.lastname: Hanari
authors.forename: Nobuyasu
authors.initials: N
authors.lastname: Itoh
authors.forename: Keiichiro
authors.initials: K
authors.lastname: Ishikawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Yarita
authors.forename: Masahiko
authors.initials: M
authors.lastname: Numata
mesh_terms: D002210:Caprylates / Q000032:analysis* / Q000737:chemistry; D005591:Chemical Fractionation / Q000379:methods*; D004784:Environmental Monitoring; D005466:Fluorocarbons / Q000032:analysis* / Q000737:chemistry; D000432:Methanol / Q000737:chemistry*; D008956:Models, Chemical; D012996:Solutions / Q000737:chemistry*
chemical_list: D002210:Caprylates; D005466:Fluorocarbons; D012996:Solutions; C023036:perfluorooctanoic acid; D000432:Methanol
keywords: Methanol solution; Methyl formate; Methyl perfluorooctanoate (MePFOA); Perfluorooctanoate; Perfluorooctanoic acid (PFOA); Storage