Most fire debris samples in the laboratory are prepared by a process known as heated passive headspace concentration. The package containing the debris is briefly opened, and a piece of activated charcoal is placed inside – suspended over, but not touching, the debris. The package is closed immediately, and placed in an incubator overnight.
The package is then taken out of the incubator, allowed to cool, and the charcoal strip is removed and placed in a vial. The charcoal strip is washed with a solvent that removes the volatile compounds from the strip and puts them into the solvent. The solvent is then analyzed by gas chromatography-mass spectrometry GC-MS).
An activated charcoal strip on a paper clip, before being suspended in a can containing fire debris
Evidence inside of an incubator