Differentiation Of Smokeless Powders Using Fourier Transform Infrared Spectrophotometry And Morphology

Differentiation of Smokeless Powders Using Fourier Transform Infrared Spectrophotometry and Morphology

Detection of Smokeless Powders Using Fourier Transform Infrared (FT-IR) and Ion Mobility Spectrometry (IMS)

Smokeless Powder Cross Section Analysis For Brand Identification

Smokeless powders are commonly used as the propellant for the home-assembly of small arms ammunition. However smokeless powders can be readily used for the manufacture of improvised explosive devices (IEDs). In the United States, pipe bombs are the most common form of IED. The smokeless powders are manufactured in a variety of granule sizes and shapes. The morphology of smokeless powders is typically tube, rod, disk, ball, flattened ball or flake. Manufacturers change the morphology of the powders to obtain a desired temperature-pressure-time path of the powder during deflagration (combustion following discharge of the ammunition in a firearm). The morphology and chemical composition (additives) of smokeless powders have been previously analyzed for forensic purposes (sample differentiation and brand identification). However, cross sectional dimensions of flattened ball-type smokeless powders have not been extensively researched. The goal of this research was to assess the forensic value of smokeless powder cross-section dimensional analysis for the characterization, differentiation, and potential brand identification of flattened ball-type powders. After granule cross sectioning was completed, digital images of the sections grains were captured. The dimensional analysis of the sections was determined using FIJI, an open-source software package.10 The tabulated data was analyzed using Microsoft Office Excel and the open-source statistical package R. The results from this pilot study show that seven of the nine powders could be differentiated by granule thickness measurements. Thus, showing that the thickness measurements are a potentially valuable metric for smokeless powder characterization and differentiation. When these data are combined with additional morphometric and chemical information, all samples could be readily differentiated.