TITLE:
Rapid Detection of Accelerants in Fire Debris Using a Field Portable Mid-Infrared Quantum Cascade Laser Based Analyzer
AUTHORS:
Hao Huang, Yongfeng Zhang, Fuqiang Dai, Xiaobo Yan, Altayeb Hamdalnile, Liyun Wu, Tingting Zhang, Haowen Li, Frank Inscore
KEYWORDS:
Quantum Cascade Laser (QCL), Mid-Infrared Spectroscopy, Fire Debris Analysis, Gasoline Vapor Detection, Ignitable Liquids
JOURNAL NAME:
Open Journal of Applied Sciences,
Vol.13 No.5,
May
25,
2023
ABSTRACT: Arson presents a challenging crime scene for fire
investigators worldwide. Key to the investigation of suspected arson cases
is the analysis of fire debris for the presence of accelerants or ignitable
liquids. This study has investigated the
application and method development of vapor phase mid-Infrared (mid-IR)
spectroscopy using a field portable quantum cascade laser (QCL) based system
for the detection and identification of accelerant residues such as gasoline,
diesel, and ethanol in fire debris. A searchable spectral library of various
ignitable fluids and fuel components measured in the vapor phase was constructed that allowed for real-time identification
of accelerants present in samples using software developed in-house.
Measurement of vapors collected from paper material that had been doused with
an accelerant followed by controlled burning and then extinguished with water
showed that positive identification could be achieved for gasoline, diesel, and
ethanol. This vapor phase mid-IR QCL method is rapid, easy to use, and has the
sensitivity and discrimination capability that make it well suited for
non-destructive crime scene sample analysis. Sampling and measurement can be
performed in minutes with this 7.5 kg instrument. This vibrational
spectroscopic method required no time-consuming sample pretreatment or
complicated solvent extraction procedure. The results of this initial
feasibility study demonstrate that this portable fire debris analyzer would
greatly benefit arson investigators performing analysis on-site.