Standoff trace explosives vapor detection at meter distances.

Area of Science:

• Analytical Chemistry
• Chemical Engineering
• Forensic Science

Background:

• Explosives vapor detection is crucial for security but challenging due to low vapor concentrations.
• Current methods like physical swiping are invasive and may miss trace amounts.
• Noncontact vapor detection offers a less invasive and potentially more sensitive alternative.

Purpose of the Study:

• To demonstrate the capability of atmospheric flow tube-mass spectrometry (AFT-MS) for standoff detection of trace explosives vapor.
• To evaluate the sensitivity and standoff distances achievable with AFT-MS combined with a high-volume air sampler.
• To explore the potential applications of this technology in security screening.

Main Methods:

• Utilized atmospheric flow tube-mass spectrometry (AFT-MS) with a high-volume air sampler.
• Performed standoff detection experiments with explosives vapor sources (RDX, nitroglycerin residue).
• Investigated detection capabilities at various distances and relative to air currents.

Main Results:

• Achieved parts-per-quadrillion sensitivity for explosives vapor detection.
• Demonstrated standoff detection of RDX vapor up to 2.5 meters and residue vapors up to 0.5 meters.
• Confirmed successful detection both upstream and downstream of the vapor source, irrespective of room air currents.

Conclusions:

• AFT-MS with a high-volume sampler enables effective standoff detection of trace explosives vapor.
• The technology offers a sensitive, noncontact method for explosives screening.
• Potential applications include security screening at mail facilities, border crossings, and checkpoints for explosives, drugs, and chemical threats.