In this study, researchers assess the extraction of ignitable liquid residues by dynamic capillary headspace sampling, with comparison to the carbon strip method.
This project investigates whether dynamic vapor microextraction (DVME) has potential as a practical alternative for fire debris analysis and lays the necessary groundwork for future validation, standardization, and implementation. This project provides a path towards unbiased, quantitative comparisons of headspace concentration methods through its use of simulated fire debris to mimic some of the complexity of authentic fire debris, while still providing the consistency needed to evaluate instrument settings. DVME is a small-volume purge and trap method that concentrates vapor phase analytes onto a short section of porous layer open tubular (PLOT) capillary coated with an adsorbent material. This project modified DVME to match the needs of fire debris analysis, specifically by demonstrating the use of realistic oven temperatures and casework containers, investigating novel methods to quantify the properties of adsorbent capillaries, and evaluating the effect of instrument settings and debris characteristics with a fractional factorial design. Debris from structural fires was assessed for the presence of ignitable liquid (IL) residue by headspace concentration followed by instrumental analysis. The project assessed the value of an alternative headspace concentration method for the extraction of ignitable liquids (IL) related to fire debris. Headspace methods provide clean samples for analytical analysis, do not require direct contact with potentially dangerous artifacts, are noninvasive, and can be non-destructive. In the US, headspace concentration is primarily conducted with the activated carbon strip (ACS) method, which requires the use of a toxic extraction solvent and is subject to vapor distortion and uses precise controllers to concentrate headspace vapors onto a capillary vapor trap and acetone as an elution solvent. Replacement of carbon disulfide will have a positive impact on the health and safety of the criminalists and forensic chemists who are part of the criminal justice system.