title: Identification of possible technical problems in determination of the major inorganic constituents of brown-rice flour by evaluating proficiency test results.
abstract: To support skill upgrading in analysis of inorganic constituents of environmental and food samples, the National Metrology Institute of Japan (NMIJ) and the National Food Research Institute (NFRI) have organized a proficiency test (PT) of determination of Mn, Fe, Cu, Zn, As, and Cd in brown-rice flour based on the international standard (ISO/IEC 17043:2010). One hundred and thirty-three sets of reports were assessed by use of the E(n)-number and z-score approaches in accordance with ISO/IEC 17043 and the international harmonized protocol for PT. The PT results and analytical procedures, reported in detail, were reviewed, and possible technical reasons for questionable or unsatisfactory results are discussed.
authors.affiliation: Environmental Standards Section, National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki, 305-8563, Japan, shinichi-miyashita@aist.go.jp.
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Miyashita
authors.forename: Kazumi
authors.initials: K
authors.lastname: Inagaki
authors.forename: Shigehiro
authors.initials: S
authors.lastname: Naito
authors.forename: Kumiko
authors.initials: K
authors.lastname: Shindoh
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Narukawa
authors.forename: Yanbei
authors.initials: Y
authors.lastname: Zhu
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Kuroiwa
authors.forename: Akiharu
authors.initials: A
authors.lastname: Hioki
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Fujimoto
authors.forename: Koichi
authors.initials: K
authors.lastname: Chiba