Introduction of a novel swabbing material of a wiper and establishment of an optimal method for the collection of organic explosive residues

The identification of explosive residues on specimens obtained from an explosion event is a crucial factor for assessing the cause of the explosion. In order to detect the components of explosives, the explosive residues deposited on surfaces are commonly extracted using swabbing materials pre-wetted with an organic solvent. The residues are then analyzed with analytical instruments such as LC/MS and CE/MS. Most conventionally used swabbing media such as cotton swabs or cotton tip swabs seem unsuitable for extracting explosive residues from the surface of a large area of clothes because the swabbing materials tend to be damaged easily, and because only a relatively small amount of explosives is collected. To overcome these problems, we have introduced a novel wiper ($215{\times}210mm$, single layer, Yuhan-Kimberly, Republic of Korea) as a swabbing material to recover representative organic explosives, namely, TNT, RDX, tetryl, HMX, PETN, and NG, from a large area of clothes. Different sides of the wiper, which was folded in half five times, was used to swab the surface of a clothing. We compared this novel wiper with a cotton swab and a cotton tip swab in terms of the recovery efficiency for the aforementioned organic explosives by pre-wetting with methanol, acetone, and acetonitrile, respectively. We identified that this novel wiper collected a significantly higher amount of organic explosive residues than a cotton swab or a cotton tip swab when using methanol as an extracting solvent.