Discussion on homogeneity assessment of reference materials based on uncertainty comparison method
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An uncertainty comparison method is proposed to assess the homogeneity of reference materials. The method compares “standard uncertainty associated with between-unit variability” (ubb) with “target standard uncertainty” (utrg) or “measurement uncertainty” (umeas) to solve the problems in assessing homogeneity of reference materials. Methods for the calculation of ubb, utrg and umeas as well as criterion for the quantitative judgment of sample homogeneity are introduced. When ubb ≤ 0.3utrg, it shows the sample is considered to be homogeneous; when 0.3utrg < ubb ≤ 0.7utrg, the sample is considered to be sufficiently homogeneous for the intended use; and when ubb > 0.7utrg, the sample is considered to be inhomogeneous. The uncertainty comparison method is compared with the F test method and shown to be more objective for the assessment of the homogeneity of certified reference materials for the chemical testing of toys.
KeywordsReference material Homogeneity assessment Uncertainty comparison method Target standard uncertainty
Funding was provided by Guangdong Science and Technology Department (CN) (Grant No. 2014A040401066) and China National Accreditation Service for Conformity Assessment (Grant No. 2014CNAS08).
- 1.ISO Guide 30:2015 Reference materials—selected terms and definitions. International Organization for Standardization (ISO), GenevaGoogle Scholar
- 2.ISO Guide 35:2006 Reference materials—general and statistical principles for certification. International Organization for Standardization (ISO), GenevaGoogle Scholar
- 3.ISO Guide 35:2017 Reference materials—guidance for characterization and assessment of homogeneity and stability. International Organization for Standardization (ISO), GenevaGoogle Scholar
- 4.Schiller SB (1996) Statistical aspects of the certification of chemical batch SRMs. NIST special publicationGoogle Scholar
- 10.ISO 13528:2015 Statistical methods for use in proficiency testing by interlaboratory comparison. International Organization for Standardization (ISO), GenevaGoogle Scholar
- 11.CPSC-CH-C1001-09.3 Standard operating procedure for determination of phthalates. Consumer Product Safety Commission (CPSC), GaithersburgGoogle Scholar
- 12.ISO 14389:2014 Textiles—determination of the phthalate content-tetrahydrofuran method. International Organization for Standardization (ISO), GenevaGoogle Scholar
- 13.EN 71-3:2013+A1:2014 Safety of toys part 3: migration of certain elements. European Committee for Standardization (CEN), BrusselsGoogle Scholar