2.2 Preparation of artificial explosive vapor and vapor
collection experiment
Each explosive was dissolved in a volatile solvent of acetone, and
explosive solutions of 4.17 μg/mL were prepared. Experiments were
carried out using a DLH-010 fume hood (410 L) of Jeiotech Co. (Republic
of Korea). The dimension of the collection matrix was 5 × 8
cm2. Explosive vapor was artificially produced by
spraying the explosive solution. A total of 5, 10, and 20 μg of the
explosive were introduced into the hood by spraying 1.2, 2.4, and 4.8 mL
of the explosive solution, respectively. These values correspond to the
explosive vapor concentrations of 12, 24, and 49 ng/L, respectively, in
the hood. The experimental procedure was as follows: (1) two sets of the
matrices were arranged at the bottom part of the hood, (2) the explosive
solution was sprayed at the top part of the hood, (3) the explosive
vapor was collected for 30 sec, and (4) IMS analysis was carried out
with the collection matrix. The generation of artificial explosive vapor
and the vapor deposition in the collection matrix are described in
Figure 1. Aerosols were formed by spraying the explosive solution, which
leads to the acceleration of acetone evaporation.
Two arrangement types of the horizontal and vertical positions of the
collection matrices were employed as shown in Figures 2 and 3,
respectively. The base side area of the hood was 90 × 64
cm2. For the horizontal arrangement, two sets of 15
collection matrices were placed at 12 cm from the wall. For the vertical
arrangement, two sets of 15 collection matrices were placed at 14 and 15
cm from the wall. Two sets of collection matrices were located at
different sites to avoid positional effects.