NCJ Number
139776
Journal
Journal of Forensic Sciences Volume: 37 Issue: 6 Dated: (November 1992) Pages: 1673-1678
Date Published
1992
Length
6 pages
Annotation
This article reports on a study that examined the durability of several materials as sources of explosive vapors after contact with TNT (trinitrotoluene) and the magnitude of surface-to-surface transfer of explosive contamination during handling.
Abstract
Study findings have investigative value because if secondary sources release substantial amounts of vapor from residue left by the primary explosive, they may provide a traceable path to concealed explosives or to recent concealments. Common building materials, including pine, cedar, spruce, fir plywood, and birch plywood, were placed in a 10-liter glass desiccator jar that also contained approximately 150 mg of TNT particles. Several aluminum plates, prepared as painted surface standards by the Environmental Institute of Michigan, were similarly exposed. There was no contact between specimens and the TNT particles. The vapor diffusion from TNT to specimen was the only available source of TNT to the specimen surfaces. The specimens remained in the jars from 20 to 90 days at ambient temperatures of approximately 24 to 27 degrees C before removal for analysis. Specimens were removed from the vapor jars, placed in plastic wrap, and hand carried to laboratories over a 24-hour period. The testing indicated that wood and painted metal exposed to TNT vapor sorb TNT and then desorb the TNT into the air for several days after removal of the source. Surface-to-surface transfer of TNT is very rapid even for rough surfaces when the surfaces are in close proximity. Further experiments are necessary to determine the change of degassing rate with time and the specific mass of TNT that can be stored on the surfaces of various materials. The nature of surface-to-surface transfer must also be investigated. 2 figures, 1 table, and 4 references