Preliminary stable isotope analyses for propellant discrimination in shotshells.

Area of Science:

• Forensic Science
• Analytical Chemistry
• Materials Science

Background:

• Determining the identity and origin of shotshell propellants is crucial for forensic investigations.
• Existing methods require enhancement for precise propellant source attribution.
• Organic component analysis and stable isotope analysis were explored for propellant characterization.

Purpose of the Study:

• To develop and validate methods for tracing the origin of shotshell propellants.
• To investigate the efficacy of bulk stable isotope analysis (BSIA) and compound-specific isotope analysis (CSIA) for propellant discrimination.
• To determine the identity and sources of various shotshell propellant samples.

Main Methods:

• Nine shotshell propellant samples from different global sources were analyzed using gas chromatography/mass spectrometry and thin-layer chromatography for organic components.
• Bulk stable isotope analysis (BSIA) was performed using elemental analysis/isotope ratio mass spectrometry without prior sample treatment.
• Compound-specific isotope analysis (CSIA) focused on nitroglycerin in double-base propellants, involving ether extraction and isotope ratio measurements via gas chromatography/isotope ratio mass spectrometry.

Main Results:

• Organic component analysis classified the nine samples into five groups, while BSIA yielded eight classification groups.
• Two samples remained indistinguishable by organic component analysis and BSIA alone.
• The subsequent application of CSIA for nitroglycerin successfully differentiated all nine samples, indicating distinct ingredients or raw material sources.

Conclusions:

• Combined stable isotope ratio analyses (BSIA and CSIA) alongside organic component analysis provide robust discrimination of shotshell propellants.
• The investigated methods successfully distinguished nine propellant samples from seven brands across four countries, suggesting diverse manufacturing origins.
• These isotope analysis techniques offer reliable results for origin tracing and identity determination of propellants.