Preliminary Investigation of Permeation Profiles of Selected Head-Space Urine Volatiles (2-Heptanone, n-Octanal) Using IMS

The late location of entrapped victims in collapsed buildings is the main reason of high mortality during urban search and rescue (USaR) operations after natural or man-made disasters. Consequently, an effort is currently being made to develop proper rescue searching tools that could improve the early location of trapped casualties. In this context, the knowledge of human scent profile and its behavior in the disaster environment is crucial. The main goal of this study was to investigate the suitability of the ion mobility spectrometry (IMS) for the quantitative monitoring of specific urine-borne volatile members of human scent interacting with the materials of collapsed dwellings. For this purpose, an ion mobility spectrometer with beta-radiation source (Ni-63) and an in-house made filling chamber mimicking the entrapment scene were employed. In preliminary experiments, quartz sand was used as imitating debris material. The experimental setup was used to investigate the permeation properties of two very promising urine-borne species, 2-heptanone and n-octanal, under the influence of two crucial operational factors; the size of quartz grain and the quartz layer thickness. 2-heptanone was found to penetrate through quartz layer by approximately a factor 4 faster than n-octanal. The twofold and threefold increase of quartz sand thickness lengthened the permeation times on average three and seven times for n-octanal, and three and five times for 2-heptanone. The presented experimental setup can be considered as a useful tool suitable for investigating the interactions of urine markers with the debris materials in the entrapment scene. However, further investigations involving different debris materials (e.g. concrete, brick, cement, wood, plastic, glass) and other urine-borne species are necessary, prior selecting a set of volatile organic compounds (VOCs) that will support the early location method of entrapped victims.