Bomb swab: Can trace explosive particle sampling and detection be improved?

Area of Science:

• Analytical Chemistry
• Materials Science
• Forensic Science

Background:

• Increasing international terrorism necessitates advanced trace explosive detection methods.
• Ion mobility spectrometry (IMS) is a key technology for detecting explosives at security checkpoints.
• Current IMS analysis relies on swabbing for residue collection, requiring optimization.

Purpose of the Study:

• To investigate factors influencing explosive residue collection via swabbing.
• To identify optimal substrate materials and swipe materials for enhanced detection.
• To understand the impact of multiple uses on swipe efficiency and contaminant profiles.

Main Methods:

• Atomic Force Microscopy (AFM) to measure explosive particle adhesion to plastic, metal, and glass.
• Evaluation of explosive adhesion to various swipe materials (Muslin, Nomex®, polyamide).
• Gas Chromatography-Mass Spectrometry (GC-MS) to analyze contaminants on swipes.

Main Results:

• Glass and metal surfaces show higher adhesion due to capillary forces, making them promising for residue collection.
• Muslin, Nomex®, and polyamide membranes are identified as superior swipe materials.
• Swipes used for 5-10 cycles demonstrated higher efficiency than new swipes due to increased surface roughness.

Conclusions:

• Surface properties and swipe material selection significantly impact explosive residue collection efficiency.
• Re-using swipes can enhance detection performance by altering surface characteristics.
• Understanding contaminant profiles is crucial for accurate IMS analysis of explosives.