Author(s)

Hao Huang¹, Yongfeng Zhang^1*, Fuqiang Dai², Xiaobo Yan¹, Altayeb Hamdalnile^3,4, Liyun Wu², Tingting Zhang², Haowen Li², Frank Inscore²

¹Shanghai Fire Research Institute of MEM, Shanghai, China.
²Micro Optical Instruments, Shenzhen, China.
³Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, China.
⁴University of Science and Technology of China, Hefei, China.

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.

Quantum Cascade Laser (QCL), Mid-Infrared Spectroscopy, Fire Debris Analysis, Gasoline Vapor Detection, Ignitable Liquids

Huang, H. , Zhang, Y. , Dai, F. , Yan, X. , Hamdalnile, A. , Wu, L. , Zhang, T. , Li, H. and Inscore, F. (2023) Rapid Detection of Accelerants in Fire Debris Using a Field Portable Mid-Infrared Quantum Cascade Laser Based Analyzer. Open Journal of Applied Sciences, 13, 746-757. doi: 10.4236/ojapps.2023.135060.