Screening of Gunshot Residue in Skin Using Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Hyperspectral Microscopy

Abstract

The detection of gunshot residues (GSR) in skin is important in criminal forensic investigations related with firearms. Conventionally, the procedure is based on the detection of metallic or inorganic residues (IGSR). In this work, we propose attenuated total reflectance Fourier transform infrared (ATR FT-IR) hyperspectral microscopy as a complementary and nondestructive technique for detection of organic GSR (OGSR). The spectra were acquired from GSR of three ammunition manufacturers, which were collected from shooter’s hands by the tape-lifting method. Before spectroscopic analysis, a Na–Ca bleach solution was added to all GSR samples on the tape for destroying skin debris. Positive detection of OGSR spectra were achieved by ATR FT-IR hyperspectral microscopy. Spectra show characteristic patterns of nitrate ester compounds which agrees with the propellant chemical composition. Characteristic ATR FT-IR spectral patterns of OGSR were measured from visualized GSR particles demonstrating the potential of ATR FT-IR hyperspectral microscopy.

Valorization of Waste Tires via Catalytic Fast Pyrolysis Using Palladium Supported on Natural Halloysite

“…Attenuated total reflectance (ATR)-Fourier transform infrared (FTIR) spectra for the pristine and modified halloysite were collected using a Nicolet is10 Thermo Scientific (USA) instrument equipped with an ATR accessory with a Ge crystal having a penetration depth of approximately 0.65 μm . The spectra were recorded using 2 mg of the sample and in the range from 4000 to 400 cm –1 with 32 scans and at 4 cm –1 resolution.…”

Innovative Vibrational Spectroscopy Research for Forensic Application

“…68 In 2020, A ́lvarez and Yańẽz published a study that focused on the use of ATR-FTIR hyperspectral microscopy for analyzing OGSRs taken from skin. 69 In this study, tape was used to collect GSR from the hand of the shooter, and a bleach solution was used to pretreat the samples. Furthermore, hyperspectral images were collected using an ATR-FTIR imaging system.…”

Interpol Review of Gunshot Residue 2019 to 2021

“…On the same topic, Alvarez et al demonstrate in Ref. [ 95 ] how hyperspectral imaging (using infrared microscopy) of a sample of hands of shooters can be used to show the presence of both IGSR and OGSR. The sample can later be used for SEM/EDS analysis as it is acquired on conductive adhesive tape.…”