Combined Collection and Analysis of Inorganic and Organic Gunshot Residues

Area of Science:

• Forensic Science
• Analytical Chemistry
• Materials Science

Background:

• Gunshot residue (GSR) analysis is vital in criminal investigations involving firearms.
• Combined analysis of inorganic (IGSR) and organic (OGSR) GSR is desirable but may impact IGSR detection.
• Existing protocols for concurrent IGSR and OGSR analysis require evaluation.

Purpose of the Study:

• To compare and evaluate three distinct protocols for the combined collection and analysis of IGSR and OGSR.
• To determine if concurrent analysis negatively affects IGSR detection.
• To identify the most suitable method for comprehensive GSR analysis.

Main Methods:

• Evaluated three protocols: modified stub, sequential recovery with two stubs, and sequential analysis from a single stub.
• Inorganic GSR (IGSR) detection utilized Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDX).
• Organic GSR (OGSR) analysis employed Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry (UHPLC-MS/MS).

Main Results:

• The sequential analysis protocol demonstrated superior performance for combined IGSR and OGSR collection and analysis.
• This method yielded a higher number of characteristic and consistent inorganic particles.
• Significantly higher concentrations of key organic compounds (ethylcentralite, N-nitrosodiphenylamine, diphenylamine, nitroglycerin) were recovered.

Conclusions:

• Sequential analysis is the most suitable protocol for the combined collection and analysis of both IGSR and OGSR.
• This approach optimizes the recovery of both inorganic and organic gunshot residue components.
• The findings support the adoption of sequential analysis in forensic laboratories for comprehensive GSR investigations.