Page 14 - A Burning Question Fire Debris

of their charged particles. The mass spectrum To test for the presence of the analyte, both ends
produced is characteristic of the sample analyzed, of the calorimetric tube are broken off and air
and this characteristic spectrum is compared to from the scene is drawn through the tube, often
a library of compounds to identify the compound by a pumping mechanism. In the presence of
present in the initial fire debris sample. the analyte the compound within in the tube will
change color. In addition, from the color change,
As laboratory analysis can be time consuming the concentration of the analyte may often be
and expensive, to aid investigators in determining estimated. Therefore, if a kerosene colorimetric
if debris samples from a fire scene warrant gas detection tube is utilized at a fire scene and a
collection and laboratory analysis for the presence color change is observed, it may be presumed that
of ignitable liquids, in some jurisdictions, fire there is kerosene present at the scene. A sample
scenes are presumptively tested for the presence would then be collected and sent to a laboratory
of ignitable liquids with colorimetric gas detection for confirmation of the presence of kerosene
tubes. These sealed glass tubes are filled with a by GC-MS. In addition, in some laboratories,
compound designed to react with a specific analyte colorimetric gas detection tubes may be utilized
of interest. For instance, a tube designed to test for as a screening tool for collected fire debris
the presence of gasoline is filled with a compound samples to determine if additional analysis is
designed to react specifically with gasoline. merited.

14 THE MYSTERY OF LYLE AND LOUISE