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Gunshot Residue

  • Page ID
    66511
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    Analysis of Handwashings for Gunshot Residue

    Objective

    To identify gunshot residue, if any, by the presence of lead on the hands.

    Sample

    Hand-swabbings:

    Have someone fire a handgun at a firing range. Immediately swab each hand with a cotton swab wetted with 0.8 M nitric acid. Swab the thumb web, palm, and back of the hand. Place each swab in a separate plastic bag and seal. Repeat the process for someone who only handled the gun after it was fired.

    Alternatively, prepare simulated hand-swabbings by adding lead nitrate solution to cotton swabs wetted with 0.8 M nitric acid. The added lead standard should contain 50 - 100 µg of lead (fired a gun) or 25-50 µg of lead (handled a gun).

    Reagents

    1000 ppm lead solution (as lead nitrate) in 1% (v/v) nitric acid; nitric acid; ammonium dihydrogen phosphate (ultrapure; matrix modifier)

    Standard Reference Material

    500 ppb lead solution (as lead nitrate) in 1% (v/v) nitric acid

    Method

    Electrothermal atomic absorption spectrophotometry

    Special equipment

    Atomic absorption spectrophotometer with graphite furnace atomizer

    Procedure

    For instructor (detailed); For student (brief)

    Typical results

    Atomic absorption calibration curve for lead

    LeadCalCurve.PNG

    Alternate Method

    Scanning electron microscopy / X-ray fluorescence (SEM-EDX)

    Procedure

    (planned for next edition)


    This page titled Gunshot Residue is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Contributor.

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