Representative Sampling of “Street” Drug Exhibits

    Volume 38, Issue 3 (May 1993)

    ISSN: 0022-1198

    CODEN: JFSOAD

    Page Count: 8


    Rodríguez, G
    Laboratory Technician, Forensic Chemist and Forensic Scientist, Criminalistics Laboratory, Institute of Forensic Sciences, San Juan,

    Colón, M
    Laboratory Technician, Forensic Chemist and Forensic Scientist, Criminalistics Laboratory, Institute of Forensic Sciences, San Juan,

    Díaz, RO
    Laboratory Technician, Forensic Chemist and Forensic Scientist, Criminalistics Laboratory, Institute of Forensic Sciences, San Juan,

    (Received 18 June 1992; accepted 27 October 1992)

    Abstract

    The value of a scientific analysis and the significance of the results are influenced by the degree to which the sample analyzed reflects the composition of the material or population under study. An appropriate methodology will result in representative sampling.

    Formulae for representative sampling protocols were evaluated, and an optimal formula to be used in a sampling plan for “street” drug exhibits with a large number of units was selected. The selected formula was applied to choose a number of sample units for routine chemical analysis of controlled substances, with the analytical result considered to be representative of the entire lot of powdered drug units in the exhibit.

    The results obtained during the research demonstrate that adoption of the formula n = 20 + 10%(N − 20) [where n = sample size, N = total population (N ⩾ 20)] can be used for selection of an appropriate representative sample from powdered street-drug exhibits. This sampling procedure results in forensic analyses of controlled substances which are supportable to a reasonable scientific certainty, and which are obtained in an efficient manner.


    Paper ID: JFS13450J

    DOI: 10.1520/JFS13450J

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    Author
    Title Representative Sampling of “Street” Drug Exhibits
    Symposium , 0000-00-00
    Committee E30