In Situ Explosive Detection Using a Miniature Plasma Ion Source and a Portable Mass Spectrometer

A small low-temperature plasma (LTP) ionization probe was coupled to a portable mass spectrometer for the rapid detection of trace explosives on surfaces. Using only a small diaphragm pump to supply ambient air to the LTP source, 100 ng each of pentaerythritol tetranitrate (PETN), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), and 2,4,6-trinitrophenylmethylnitramine (Tetryl) were detectable on glass in under 1 minute. The main ion signal from these molecules (M) is the M + NO₃]^? species. While much optimization remains, it is believed that this miniature LTP source will remove the need for external gas cylinders and additional heating for in situ explosives detection using portable mass spectrometers.