STP540: Role of Homogeneity in Powder Sampling

    Grant, CL
    Professor of chemistry and chemist, Center for Industrial and Institutional Development, Kingsbury Hall, University of New Hampshire, Durham, N.H.

    Pelton, PA
    Professor of chemistry and chemist, Center for Industrial and Institutional Development, Kingsbury Hall, University of New Hampshire, Durham, N.H.

    Pages: 14    Published: Jan 1973


    Abstract

    When chemical analyses fail to satisfy the precision and accuracy requirements of a problem, it is common to attribute this difficulty to heterogeneity. In this paper, relationships between the properties of samples and standards and the methods used to analyze them are examined with respect to the influence of homogeneity.

    The majority of chemical analyses are intended to characterize bulk composition. In this situation, a homogeneous material is one in which the unit that determines segregation is “very small” compared to the size of the analytical sample and in which the defining units are randomly distributed in the bulk. Both theoretical and experimental evidence is presented to demonstrate the magnitude of error contributed by various sizes of analytical samples and segregation units.

    The error contributed by heterogeneity cannot be completely eliminated. Therefore, the analyst must attempt to devise a total analytical system with an acceptable sampling error.

    Keywords:

    homogeneity, samples, powder (particles), standards, sampling


    Paper ID: STP34744S

    Committee/Subcommittee: E02.04

    DOI: 10.1520/STP34744S


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