Differentiation of bullets by spark source mass spectrometry

Area of Science:

• Forensic Science
• Analytical Chemistry
• Materials Science

Background:

• Bullet identification is crucial in forensic investigations.
• Conventional methods rely on physical markings, which can be altered or ambiguous.
• Elemental composition offers a potentially more robust basis for differentiation.

Purpose of the Study:

• To evaluate the capability of spark source mass spectrometry (SSMS) for differentiating bullets based on their elemental composition.
• To compare SSMS with other analytical techniques like neutron activation analysis for forensic applications.

Main Methods:

• Spark source mass spectrometry (SSMS) was employed to analyze the elemental composition of bullet lead.
• Photographic detection was used for SSMS analysis.
• Quantitative characterization focused on twelve key elements present at or above 0.1-ppm levels.

Main Results:

• Twenty-six elements were commonly detected in bullet lead, with twelve proving useful for quantitative analysis.
• SSMS exhibited a precision of approximately 10% relative standard deviation and an average error of 30%.
• Distinct elemental composition groups were identified within bullet boxes, with some commonalities observed across different manufacturing lots.

Conclusions:

• Despite accuracy limitations, SSMS is superior to neutron activation analysis for bullet differentiation due to its ability to determine a larger number of elements.
• The non-uniform elemental composition within bullet batches allows for effective grouping and identification.
• SSMS presents a promising alternative to traditional methods for identifying bullets in forensic science.