Soil examination for a forensic trace evidence laboratory - Part 2: Elemental analysis

Area of Science:

• Forensic Science
• Analytical Chemistry
• Geoscience

Background:

• Forensic laboratories commonly use Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDX) and X-ray Fluorescence Spectroscopy (XRF) for elemental analysis.
• Laser-Induced Breakdown Spectroscopy (LIBS) is an emerging technique gaining traction for elemental profiling, particularly for glass fragments in forensic contexts.

Purpose of the Study:

• To compare the discrimination power of LIBS, XRF, and SEM/EDX for analyzing Australian soil specimens.
• To evaluate the suitability of these elemental analysis techniques for differentiating soil samples in forensic trace evidence examinations.

Main Methods:

• Elemental analysis of 29 Australian soil specimens (12 from Canberra, 17 from other Australian sites).
• Application and comparison of Laser-Induced Breakdown Spectroscopy (LIBS), X-ray Fluorescence Spectroscopy (XRF), and Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDX).

Main Results:

• All three analytical methods (LIBS, XRF, SEM/EDX) demonstrated strong discrimination capabilities for the analyzed soil specimens.
• Excellent discrimination results were achieved across all tested elemental analysis techniques.

Conclusions:

• Any of the evaluated elemental analysis techniques (LIBS, XRF, SEM/EDX) can be effectively employed in trace evidence laboratories.
• These methods can serve as integral components of broader examination protocols for differentiating soil specimens based on elemental composition.