Developments in Arson Analysis: A Comparison of Charcoal Adsorption and Direct Headspace Injection Techniques Using Fused Silica Capillary Gas Chromatography

Abstract

Abstract Procedures that have been explored for the extraction or concentration or both of fire accelerant materials from arson residues include direct headspace injection, steam distillation, charcoal adsorption followed by thermal or solvent elution, and on-column headspace injection of vapor samples, combined with cryogenic focusing. Because of the advantages to be gained from improved separations and increased sensitivity, it seemed advisable to use capillary column gas chromatography with whatever method was ultimately selected. The results of previous studies led to a decision to compare (1) a modified carbon wire adsorption technique and (2) cryogenic focused vapor samples directly injected on-column. Based on our experiences with the charcoal and cryogenic focusing techniques (in presence of water), the cryogenic method is an appropriate and satisfactory technique. Concentration methods (for example, distillation and adsorption) have been faulted for engendering quantitative and qualitative changes in the sample. Direct headspace injections of the type investigated here exercise less effects. They are simple to perform, require minimum sample preparation, and result in superior case sensitivity.