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.