Adsorption saturation and chromatographic distortion effects on passive headspace sampling with activated charcoal in fire debris analysis

    Authors

    M. R. Williams; D. Fernandes; C. Bridge; D. Dorrien; S. Elliott;M. Sigman

    Comments

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    Abbreviated Journal Title

    J. Forensic Sci.

    Keywords

    forensic science; fire debris; activated charcoal; passive headspace; CARBON; POLARIZABILITIES; HYDROCARBONS; Medicine, Legal

    Abstract

    Distortion of the chromatographic profile obtained for hydrocarbons that have been sampled by adsorption onto activated charcoal is a well-known phenomenon. The work reported here helps to better define the causes of chromatographic profile distortion and offers a potential method to avoid chromatographic distortion in some cases through a subsampling technique. The recovery of hydrocarbons from an equimolar mixture was investigated to determine the influence of hydrocarbon concentration on the molar ratios of recovered components. In a one-quart container, hydrocarbon volumes as small as 24 muL (liquid) were sufficient to saturate the surface area available for adsorption on a 99.0 mm(2) square of activated charcoal, resulting in significant distortions in the molar ratio and the chromatographic profile of the recovered hydrocarbons. Passive headspace sampling of a similarly small volume of unweathered gasoline spiked onto carpet padding resulted in a significant distortion of the chromatographic profile. The chromatographic profile of the recovered hydrocarbons closely resembled 75% weathered gasoline. Heating the container spiked with unweathered gasoline to evenly distribute the components and then removing a subsample of the carpet padding to a second container for passive headspace analysis greatly reduced the amount of distortion in the resulting chromatogram.

    Journal Title

    Journal of Forensic Sciences

    Volume

    50

    Issue/Number

    2

    Publication Date

    1-1-2005

    Document Type

    Article; Proceedings Paper

    Language

    English

    First Page

    316

    Last Page

    325

    WOS Identifier

    WOS:000227488900008

    ISSN

    0022-1198

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