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The Influence of Swabbing Solutions on DNA Recovery from Touch Samples,

Authors

  • Sarah M. Thomasma M.S.,

    1. Forensic Science Program, School of Criminal Justice, Michigan State University, East Lansing, MI
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  • David R. Foran Ph.D.

    Corresponding author
    1. Forensic Science Program, School of Criminal Justice and Department of Zoology, Michigan State University, East Lansing, MI
    • Forensic Science Program, School of Criminal Justice, Michigan State University, East Lansing, MI
    Search for more papers by this author

  • Presented in part at the 62nd Annual Meeting of the American Academy of Forensic Sciences, February 22–27, 2010, in Seattle, WA.
  • Co-author S. Thomasma was funded, in part, by Howard Hughes Medical Institute grant 52006304 through the Precollege and Undergraduate Science Education Program.

Additional information and reprint requests:

David R. Foran, Ph.D.

Forensic Science Program

School of Criminal Justice and Department of Zoology

560 Baker Hall

Michigan State University

East Lansing, MI 48824

E-mail: foran@msu.edu

Abstract

There has been minimal research into how to best obtain DNA from touch samples. Many forensic laboratories simply moisten a swab with water and use it for collecting cells/DNA from evidentiary samples. However, this and other methods have not been objectively studied in order to maximize DNA yields. In this study, fingerprints were collected using swabs moistened with water or laboratory or commercially available detergents, including sodium dodecyl sulfate (SDS), Triton X-100, Tween 20, Formula 409®, and Simple Green®. Prints were swabbed, DNA isolated using an organic extraction, yields quantified, and relative yields compared. In all cases, the detergent-based swabbing solutions outperformed water, with SDS and Triton X-100 producing significant increases in yield. Short tandem repeat profiles were consistent with the individuals that placed them. Subsequent analysis of SDS concentrations for collecting touch DNA demonstrated an increase in DNA yield with increasing SDS concentration, with an optimal concentration of approximately 2%.

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