Electrospray ionization tandem mass spectrometry for the detection and characterization of smokeless powders

Smokeless powder is one of the most common types of explosives used today in civilian ammunition and because of this it is also commonly found in improvised explosive devices. Thus, the detection of smokeless powder in the form of unexploded powder or residue from a gunshot or post-blast explosion can be of great forensic value. Tandem mass spectrometry (MS/MS and MS n) in a quadrupole ion trap with electrospray ionization was examined in order to develop a method for the routine, rapid identification and comparison of smokeless powder. This method was optimized for the simultaneous detection of the smokeless powder stabilizers methyl centralite, ethyl centralite, and diphenylamine and it was found that good limits of detection could be achieved for all three stabilizers. Seven smokeless powder samples and their residues were then analyzed as 'real world' samples. The use of tandem mass spectrometry and selected reaction monitoring increased the sensitivity and selectivity, respectively, of this technique for both the unburned and burned powders, allowing for the identification of trace components. Mass spectrometry was able to identify all of the unburned powder samples as being smokeless and it was able to identify gunshot residue at firing distances of 3" and 12" on unwashed, hand washed (in deionized water), and machine washed cloth. All but two of the unburned powders could be differentiated from each other by combining the mass spectrometry data with the physical characteristics and extraction tendencies of the smokeless powders.