Gunshot Residue Analysis by Micellar Electrokinetic Capillary Electrophoresis: Assessment for Application to Casework. Part I

Usually gunshot residue (GSR) analysis examines samples for the presence of inorganic primer compounds, in particular lead (Pb), barium (Ba), and antimony (Sb). Alternative methods are needed because of the advent of primers that do not contain these metals. Micellar electrokinetic capillary electrophoresis (MECE) has been used to examine characteristic organic gunpowder components (COGC), including nitroglycerin (NG). diphenylamine (DPA), ethylcentralite (EC), and others. The purpose of this project was to develop MECE for implementation in GSR casework. In order to do this, it was necessary to: (a) establish a sample collection and preparation method for use with both MECE and scanning electron microscopy (SEM); (b) determine that the minimum detection limits for COGC were in the picogram range; (c) show that no residues were identified in samples from the general population at or above these levels; and (d) quantitatively identify the common chemicals used in more than 100 commercially available ammunitions and reloading powders. Results from the study covering organic GSR persistence, environmental exposure effects, comparison to SEM results, and casework using both CE and SEM are described in a subsequent paper.