Organic gunshot residues, specifically methyl centralite (1,3-dimethyl-1,3-diphenylurea) and ethyl centralite (1,3-diethyl-1,3-diphenylurea), are characteristic compounds that forensic analysts look for when determining potential shooters. These distinctive compounds have long been analyzed by a number of instrumental techniques, many which involve extensive sample preparation or have lengthy analyses times. Presented here is an ambient ionization method that requires no sample preparation, offers real-time analysis, and can be paired with a portable ion trap mass spectrometer for <i>in-situ</i> analysis. Touch swab spray ionization utilizes a rayon tipped swab that has an aluminum wire handle which can be simply swabbed over the area of interest. The swab after contacting the hands of the shooter, or other area, simply has solvent applied to the rayon tip and a high voltage applied to the aluminum handle. This process creates the ions that the mass spectrometer will use to determine if the organic gunshot residue is present. Additional benefits of touch swab spray ionization are the swabs are commercially available, they are sterile and they are individually packaged to prevent contamination. The swabs are also forensically feasible as they are sealed prior to delivery by the vendor with a tamper proof label. Here we have shown that this ambient ionization method allows for the direct swabbing of the hands of suspected shooters for trace residues and confirm the presence of the two organic gunshot residues tested.

Swab spray mass spectrometry for rapid analysis of organic gunshot residue from human hand and various surfaces using commercial and fieldable mass spectrometry systems

254th National Meeting (2017)

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