NCJ Number
89288
Journal
Arson Analysis Newsletter Volume: 6 Issue: 6 Dated: (November 1982) Pages: 105-140
Date Published
1982
Length
35 pages
Annotation
This research developed a method for collecting evidence of the use of an accelerant while the fire is in progress, so as to increase the likelihood of detecting the presence of accelerants and eliminate lapse time between the fire and later tests.
Abstract
The sample collection procedure uses a portable battery-powered air pump that can be carried in a fire fighter's coat pocket. A sample of the fire atmosphere is pulled into the suction side of the pump through a small piece of tubing that contains two adsorber beds in series. The first adsorbent bed that the incoming gas sample contacts contains anhydrous calcium sulfate. This adsorber removes most of the water vapor from the gas sample. After leaving the calcium sulfate adsorber, the gas sample enters a bed of activated silica gel, which adsorbs any organic compounds in the gas with an efficiency greater than 90 percent. The gas sample is then exhausted through the pump. The silica gel and calcium sulfate tubes are removed from the pump, capped, and sent to a laboratory for analysis. An analysis of the compounds adsorbed on the silica gel bed can be effected by heating the silica gel to 200 degrees centigrade in a sealed vial containing a Teflon septum. A sample of the gaseous contents of the vial is obtained by piercing the septum with a hypodermic syringe. The sample is then analyzed with a gas chromatograph. In a fire atmosphere produced by the burning of common woods, it is relatively easy to detect the presence of hydrocarbon accelerants; however, a fire atmosphere produced by burning synthetic materials that contain many hydrocarbon compounds creates a complex background chromatogram from which it is difficult to identify accelerant components. Under these circumstances, it is necessary that a more sophisticated analytical technique than gas chromatography be used in the identification stage. Graphic data from the research are appended. (Author summary modified)