Detection of Organic Gunshot Residues from human hands using DSA‐TOF

The organic gunshot residues (OGSRs), specifically methyl centralite (MC; 1,3-dimethyl-1,3-diphenylurea), ethyl centralite (EC; 1,3-diethyl-1,3-diphenylurea), 2,4-DNT (2,4-dinitrotoluene), and TNT (trinitrotoluene), are characteristic compounds for which forensic analysts test determining if a person has discharged a firearm. A set of 200 samples from 50 shooters were collected as part of the validation study. Pistol 9 mm and special revolver .38 were fired at indoor and outdoor shooting ranges. The development of a methodology based on direct analysis of samples-time of flight-mass spectrometry (DSA-TOF-MS) made it possible to identify the main components of organic shot residues, which gave the possibility to introduce a new method of analysis of shot residues in the Chilean supply area. The DSA-TOF-MS provided extensive information on the composition of the shot residues: MC, EC, 2,4-DNT, and TNT. Samples taken from the trigger hands required minimal sample preparation that reduced analyses time. With the implementation of new alternative analytical methodologies, a great step would be taken in the analysis of OGSRs, because now there is no such technique for its analysis in Chile, and the results would also complement the existing inorganic elemental analyses generated during a gunshot.