Coupling Gas Chromatography (GC) and Vacuum Ultraviolet (VUV) Spectroscopy for Forensic Applications

As submitted by the proposer:

When conducting forensic analyses, three crucial factors for the analytical methods come into play. These factors are sensitivity, selectivity, and specificity; they relate to the extent of an instrument’s response, the ability of the instrument to respond to analytes in mixtures, and the ability to unambiguously identify the analyte.

In the field of forensic chemistry, techniques such as Fourier Transform Infrared (FTIR) spectroscopy and mass spectrometry (MS) are commonly used to generate highly-complex spectra that exhibit discernible changes based upon small structural differences. In preliminary work, the researchers have already identified several controlled substances that yield indistinguishable electron impact (EI) mass spectra but are easily distinguished based upon their absorbance in the vacuum ultraviolet (VUV) range. The researchers have also observed that a surprising amount of fine structure appears in the VUV spectra of nitrate ester explosives such as nitroglycerin and ethylene glycol dinitrate (EGDN). VUV spectroscopy has also been demonstrated to differentiate various alkylbenzenes in fuels such as gasoline.

Therefore, the purpose of this project is to formally establish VUV spectroscopy as a completely new way to identify compounds of forensic interest as they elute from a gas chromatograph. The data provided by VUV are sensitive, selective, and have the potential to be more specific than mass spectrometry for several analytes. The researchers will achieve this goal in three large stages: 1) assemble a GC system with a VUV detector; 2) qualify and optimize performance of the GC/VUV; and 3) demonstrate the applicability of GC/VUV to forensic samples.

Note: This project contains a research and/or development component, as defined in applicable law, and complies with Part 200 Uniform Requirements - 2 CFR 200.210(a)(14).

ca/ncf