4 CONCLUSIONS
A test method for vapor collection efficiency and IMS detection of
explosives with low vapor pressure such as TNT, RDX, and PETN was
developed using artificial explosive vapor and collection matrices.
Explosive vapor was generated by spraying the explosive solution in
acetone, and the collected vapor was detected using IMS. Of the 15
collection matrices, only the SSM, PFS, and LCP showed the TNT and/or
RDX ion peaks in the IMS spectra at explosive vapor concentration of
lower than 49 ng/L. PETN was not detected up to a vapor concentration of
49 ng/L because of the low desorption capability. For the SSM, only TNT
at 49 ng/L of vapor concentration was detected for the horizontal
arrangement. For the PFS, 49 ng/L of TNT and RDX vapors were observed in
the IMS spectra. For the LCP, TNT was detected at 24 ng/L of vapor
concentration and RDX was observed at 49 ng/L of vapor concentration.
The detection limits of explosive vapors were significantly poorer than
those for solid-state explosives owing to the difference in the
introduction efficiencies. The adsorption and desorption capabilities
could be factors that influence the explosive vapor detection
efficiency. The factors affecting the adsorption capability of the
collection matrix are area, material, and structure. The contributing
factors related to the desorption capability are chemical interactions,
thermal conductivity, thickness, and structure. The test method
developed in this study can be used for evaluating vapor collection
efficiency and IMS detection of hazardous materials with low vapor
pressure and may be applied to on-site trace chemical vapor detection.