title: Certified reference material of volatile organic compounds for environmental analysis: BTEX in methanol.
abstract: The Brazilian Metrology Institute (National Institute of Metrology, Quality, and Technology, Inmetro) has been developing a certified reference material (CRM) of the volatile organic compounds benzene; toluene; ethylbenzene; and ortho, meta, and para-xylenes (BTEX) in methanol, to ensure quality control for environmental-analysis measurements. The objective of this paper is to present the results of certification studies: uncertainty estimates related to characterization, a homogeneity study, and a stability study on a single lot of CRM composed of BTEX in methanol. The method used analysis of variance (ANOVA), a statistical tool, to evaluate the homogeneity and stability of the BTEX CRM, which complies with ISO Guide 30 series. The homogeneity and stability of the BTEX CRM was confirmed for all analytes and their respective properties. All the procedures used in this study complied with ISO GUIDE 34, ISO GUIDE 35, and the guide to the expression of uncertainty of measurement (GUM).
authors.affiliation: National Institute of Metrology, Quality and Technology -INMETRO, Division of Chemical Metrology, 25250-020, Duque de Caxias, RJ, Brazil, laneves@inmetro.gov.br.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Neves
authors.forename: Renato R R
authors.initials: RR
authors.lastname: Almeida
authors.forename: Eliane P
authors.initials: EP
authors.lastname: Rego
authors.forename: Janaína Marques
authors.initials: JM
authors.lastname: Rodrigues
authors.forename: Lucas Junqueira
authors.initials: LJ
authors.lastname: de Carvalho
authors.forename: Ana Letícia
authors.initials: AL
authors.lastname: de M Goulart
mesh_terms: D000704:Analysis of Variance; D001554:Benzene / Q000032:analysis; D001555:Benzene Derivatives / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods / Q000592:standards*; D000432:Methanol / Q000032:analysis; D012015:Reference Standards; D014050:Toluene / Q000032:analysis; D035501:Uncertainty; D055549:Volatile Organic Compounds / Q000032:analysis* / Q000592:standards*; D014992:Xylenes / Q000032:analysis
chemical_list: D001555:Benzene Derivatives; D055549:Volatile Organic Compounds; D014992:Xylenes; D014050:Toluene; C031286:4-xylene; D001554:Benzene; C004912:ethylbenzene; D000432:Methanol