Gunshot residue (GSR) analysis is a crucial aspect of the investigation of firearms-related incidents. The presence of GSR on a person or surface can provide valuable insight regarding proximity or involvement of an individual in a shooting incident. Traditionally, GSR analysis relies on the detection of inorganic compounds within the ammunition, known as inorganic gunshot residue (IGSR). These inorganic compounds are comprised of lead, barium, and antimony. IGSR compounds originate from the content of the primer, and each individual element is expelled during discharge, fused while molten, and land on nearby surfaces. Stubs with an adhesive coat are used to collect these particles by pressing against a surface suspected to have GSR particles. The current analytical method for detection and identification of IGSR, Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy (SEM/EDS), surveys GSR stubs for both the elemental composition as well as the morphology of the compounds. Positive identification requires both the elemental composition and spherical morphology of IGSR.
Several issues exist with the nature of IGSR as well as the current method of analysis. Identification by SEM/EDS not only requires time for transportation and labor but may also produce false negatives due to inconsistent shape or lack of all three elements. The development of a rapid and robust analytical technique would address these deficiencies. Mass spectrometry (MS) is a standard analytical technique known for its specificity and accuracy. New advancements in research and technology have produced the ability to miniaturize MS while retaining its superior capabilities in identification.
The characteristics of IGSR also pose issues in terms of validity, such as specificity to discharging a weapon, and ability to be transferred or wiped off. Qualities such as these can lead to both false negatives and false positives. In recent years, advances in forensic science research have studied the composition of organic gunshot residue (OGSR) as well as new methods for detecting these compounds. Research has pointed towards advantages in OGSR that would rectify the analytical issues seen in using IGSR as the target compound. Some qualities of OGSR that would improve GSR detection are its specificity to GSR, the molecular complexity of its components, its higher persistence on surfaces, and lower transferability.
This study addressed both issues by employing the MX908 High Pressure Mass Spectrometer and developing an analytical method for major OGSR targets. The objective of this research was to test the MX908’s ability to ionize and detect Nitroglycerin (NG), Diphenylamine (DPA), Ethyl Centralite (EC), Dibutyl Phthalate (DBP), and Nitroguanidine (NQ). Furthermore, these experiments tested a range of voltage parameters to achieve optimal fragmentation, and ultimately an accurate and specific analytical method.
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/48386 |
| Date | 11 March 2024 |
| Creators | Timmerman, Angela Michelle |
| Contributors | Hall, Adam B. |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
| Rights | Attribution-NonCommercial-ShareAlike 4.0 International, http://creativecommons.org/licenses/by-nc-sa/4.0/ |
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