Adsorption/desorption GC assisted with retention index comparison of peaks for the identification of accelerants in fire residues

The authors present both an efficient sample preparation procedure and a highly discriminating gas chromatographic (GC) method for the identification of accelerants in fire residues. A purge-and-trap concentrator fitted with a carbotrap adsorbent tube was used to preconcentrate the accelerants from various fire residues. The resultant sample tubes were submitted to a thermal desorption unit (TDU) which was connected to a dual wide-bore capillary column GC. The identification of the accelerants was based on both a retention indices comparison and chromatogram pattern recognition. The advantages and disadvantages of this dynamic adsorption/desorption procedure were evaluated by comparison with other pretreatment procedures such as charcoal tube adsorption/CS₂ extraction and continuous steam distillation