NCJ Number
218478
Journal
Journal of Forensic Sciences Volume: 52 Issue: 3 Dated: May 2007 Pages: 579-585
Date Published
May 2007
Length
7 pages
Annotation
This study determined which of three types of containers (metal "paint" cans, glass mason jars, and polymer bags) provided the most vapor-tight seal for the prevention of vapor loss from ignitable liquid collected at an arson scene, as well as the best protection from cross-contamination.
Abstract
The study found that the most vapor-tight container was a properly heat-sealed copolymer bag. Glass jars had the fastest leak rate, followed by metal paint cans and properly heat-sealed polymer bags. Each container had a different leak mechanism, which had an observable effect on the composition of hydrocarbons lost from the container. Hydrocarbon transfer from one container to another was also demonstrated. The properly heat-sealed copolymer bags retained all of the hydrocarbons; however, the study did not test for leaking with other liquids, such as oxygenates, to determine whether they behaved in a similar manner. Over time, leaking jars that contain hydrocarbons can cross-contaminate one another if stored in close proximity. Also, hydrocarbons from the immediate environment can penetrate the jar. This study used the method of passive headspace concentration of ignitable liquids onto activated charcoal, which can result in quantitative sampling errors unless care is taken to address these problems. The dynamic exchange of hydrocarbon molecules on the activated charcoal as well as any potential loss of the hydrocarbon molecules from the activated charcoal was examined to reveal any effects these processes might have on the interpretation of the results. Leak rates for the three types of containers were determined under carefully specified conditions, which are described in detail in this report. 11 figures and 13 references