Presentation Profile
Vacuum Ultraviolet (VUV) Absorption Spectroscopy: a novel method in the forensic analysis of fire debris evidence
Currently Scheduled: 1/18/2018 - 11:15 AM - 11:35 AM
Room: Room 382 C
Main Author
Adam Hall B. Ph.D. - Northeastern University
- Sarah Pina - Northeastern University
- James Diekmann - VUV Analytics, Inc.
- Tom Steen - VUV Analytics, Inc.
- Paul Johnson - VUV Analytics, Inc.
Abstract:
This research interfaced a VUV Analytics VGA-100 VUV spectroscopy detector to an Agilent 6890N gas chromatograph. This detector allows for the generation of high quality absorption data between 125-240 nm by using coated reflective optics and a charge coupled device light path to assess absorption across the VUV spectrum. Spectral filters allow for class discrimination of hydrocarbon-containing compounds by providing enhanced visualization of unresolved chromatographic species. This is a distinct advantage, especially for characterizing complex hydrocarbons in petroleum-derived products such as gasoline. VUV Analytics VUV AnalyzeTM analysis software engine allows for easy peak identification, as well as analysis of mass and volume percent of compound classes and carbon number class within the analyzed fuel samples. The unique software and detection capabilities were utilized to assess VUV absorption spectroscopy as a viable method for distinguishing gasoline brands. GC-VUV data for 0%, 25%, 50, and 75% evaporated samples was produced for numerous gasoline sources obtained from local stations to assess both neat and weathered samples. Mass percentages of carbon number classes were generated by VUV Analytics VUV AnalyzeTM software. The VUV PIONA+TM application software plug-in is optimized for gasoline analysis and utilizes proprietary retention index files to identify the mass percent of parafins, isoparafins, olefins, naphthenes, and aromatics (PIONA), as well as the mass percent of each carbon number class, i.e. the percentage of C6s, C7s, etc. The generated data was evaluated to determine if the VUV PIONA+TM software could be used for brand differentiation based on carbon number class and associated spectral features. During this presentation, data will be shown highlighting differences of 2-15% in PIONA mass percentages for the same hydrocarbon classes of different brands. A detailed characterization based on mass percentages of hydrocarbon classes represents a new and exciting dimension in fire debris and ignitable liquid analysis for the field of forensic science.
