Substrate Database


Substrate Materials Sample Preparation

Samples are approximately 6 cm x 6 cm in size. Samples are prepared un-heated (unburned)and heated (burned). The heated samples are produced by a modified destructive distillation method based on a method developed by the State of Florida Bureau of Forensic Fire and Explosives Analysis. Samples are placed up side down in an un-lined metal quart paint can in which the lid with nine 1 cm diameter holes is placed loosely onto the can. Heat is applied to the bottom of the can by a propane torch held 4 cm from the bottom of the can. Once smoke appears from the can, heat continues to be applied for an additional 2 minutes. After the 2 minutes, the heat is removed and the lid is replaced with a solid lid to allow vapors within the headspace to condense as the can temperature returns to room temperature.


The interfering products from the heated and un-heated substrate materials are collected by passive headspace adsorption onto activated carbon following the ASTM E 1412 standard method. An activated carbon strip (10 mm x 22 mm) is suspended into the headspace of the can by a paperclip and un-waxed dental floss. The sealed can is heated for 16- 18 hours at 66ºC. Once cooled to room temperature, the activated carbon strip is removed from the can and cut in half. One half is archived and the other is deposited into a vial with 1/2 ml of carbon disulfide for analysis.