Identification of Gunshot Residues in Fabric Targets Using Sector Field Inductively Coupled Plasma Mass Spectrometry Technique and Ternary Graphs*

Abstract

During criminal investigations involving firearms, the detection of gunshot residues (GSRs) is one of the most important evidences. In the present study, a new method to identify trace evidences of GSRs, deposited around the bullet entrance hole, in different types of fabrics used as targets, is described. The experiments were carried out using a 0.38-inch caliber revolver, and 9-mm and 0.40-inch caliber pistols. Testimonies of 2.25 cm(2) of the fabrics were cut around the bullet entrance and digested with 10% nitric acid. Antimony, barium, and lead were analyzed in the remaining solution using a sector field inductively coupled plasma mass spectrometer. The concentrations of the elements were detected at levels up to few microgram per square centimeter. The use of ternary graphics allowed us to identify specific patterns of distribution for blank samples and the clear distinction between the revolver and pistols used.

Comparison of Different Swabs for Sampling Inorganic Gunshot Residue from Gunshot Wounds: Applicability and Reliability for the Determination of Firing Distance

“…Indeed, Ba/Pb, Ba/Sb, and Sb/Pb ratios occur in the range of 90–140, 1.9–2.4, and 40–60, respectively, in the case of IGSR. The use of a ternary graph may further improve the discrimination between IGSR and nonrelated GSR . However, although ICP techniques are becoming crucial in forensic identification and quantification of IGSR , SEM‐EDX is sometimes used to confirm the results obtained.…”

Detection of Gunshot Residues Using Mass Spectrometry

“…Freitas et al examined the use of ICP-MSF-MS to study the possibility of differentiating weapons and ammunition based on the IGSR detected on different fabrics [79]. The results demonstrated that GSR does not persist on different fabrics reproducibly, as no significant differences in Sb, Ba, and Pb levels were found between the five tested fabrics, that is, microfiber, flannel, canvas, tergal (a polyester), and tricoline (a variety of cotton).…”

“…Fabric blanks showed a significantly lower concentration of the three GSR characteristic compounds than fabric samples after shooting. Using ternary graphs, the authors could clearly distinguish fabrics before and after shooting and a characteristic pattern of distribution for pistols and round-barrel revolvers was determined [79]. …”

Analysis Gunshot Residue (GSR) – Reconstruction of Crime Scenes

“…Recently a few studies are reported to explain the chemical nature of the GSR particles using XPS and ToF-SIMS (8)(9)(10)(11)(12)(13)(14). GSR on fabrics is very recently studied by Joao Carlos by inductively couples plasma spectroscopy [8]. X-ray photoelectron spectroscopy (XPS) can provide important information regarding the surface chemistry of GSR because of its nanometer-scale sampling depth [9].…”