Non-toxic Ammunition Research Articles

Voltammetric analysis of luminescent markers in gunshot residues.

Currently, SEM-EDS is used to detect gunshot residue (GSR) from the presence of Ba, Pb, and Sb in the sample. However, the development of new nontoxic ammunition (NTA) has prevented conventional metals from being found. In this work, we aim to determine the presence of an inorganic luminescent chemical marker based on rare earth in gunshot residues using the technique of squarewave voltammetry (SWV). After firing, the luminescent complex [(Eu2 Zr)(btc)3 (Hbtc)0.5 .6H2 O], which is used as a chemical marker, can be detected under a UV lamp. An aqueous solution with 0.1mol L-1 KCl as supporting electrolyte can be easily collected on carbon paste electrode surfaces for SWV analysis A=100 mV, f=10Hz, and step potential of 5mV are required. The luminescent marker incorporated into the carbon paste electrode showed two anodic peak currents in the region of 0.4V (vs Ag/AgCl) and at 0.75 V (vs Ag/AgCl) and also a cathodic one in 0.4V (vs Ag/AgCl). SEM-EDS was able to analyze the same voltammetric results for conventional and nontoxic ammunition containing the luminescent marker. Therefore, voltammetry and SEM-EDS are valid for detecting the new residue marker in GSR. Despite this, the electrochemical method is still more advantageous because of its low cost and lack of expensive equipment and supplies in forensic laboratories.

Spectrophotometric Analysis of Nitrite in Gunshot Recentness Examinations from Non Toxic Ammunitions: Expanding the Frontiers of Forensic Chemistry

Nitrite ions consist on an important chemical clue related to gunshot examination, concerning to estimation of the time since discharge. Current forensic laboratory methods for nitrite analysis in gunshot residues are well established for investigating conventional ammunition residues. However, the use of these methods to analyze the so-called ecological or “non-toxic” ammunition has been less studied. Here, we have developed a spectrophotometric flow injection analysis method to test nitrite in samples of “non-toxic” ammunition residues. The ammunition used in these experiments was the NTA (non-toxic ammunition) model, .38 caliber, We also investigated the kinetics of nitrite decomposition for this type of ammunition over time. Sulfanilic acid and 1-naphthylethylenediamine in acetic acid were used as colorimetric reagents. The linear dependence of the spectrophotometric signal on the nitrite concentration was as follows: A = 2.07 x 104 µmol-1 L [NO2-] + 6.78 x 10-3 with a correlation coefficient (r) of 0.9994. The standard deviation (SD) of the analytical curve was 3.17 x 10-3 resulting in a limit of detection (LOD) = 0.46 µmol L-1 and a limit of quantification (LOQ) = 1.56 µmol L-1. The proposed instrumental method was more sensitive than conventional colorimetric tests and permitted the detection window to be extended to 32 days while ensuring the safety and reliability required for forensic analysis, in comparison to 7-10 days usually proposed for conventional ammunition. Therefore, the proposed method can be safely employed in forensic laboratories for routine analysis of nitrite ions in GSR samples from ecological or “non-toxic” ammunition.

Nontoxic ammunition: Challenges and perspectives for GSR identification

AbstractGunshot residues (GSR) are one of the most important forensic traces in crimes involving firearm discharge, being the conventional GSR characterized by containing spheroidal particles composed of Pb, Ba, and Sb. Over the years, a wide range of techniques has been applied and improved to characterize the conventional GSR, with deserved emphasis on scanning electron microscopy coupled with energy‐dispersive x‐ray spectroscopy (SEM/EDS). However, the introduction of nontoxic ammunition (NTA), or heavy metal‐free (HMF), on the market has triggered a search for new methodologies for GSR identification since methods based on the chemical and/or morphological profiles of conventional GSR are no longer appropriate for the analysis of this type of residues. This review highlights current methods and proposals for characterization of GSR from NTA, which involve either the search for characteristic chemical profiles or the insertion of selective markers in this new type of ammunition.This article is categorized under: Forensic Chemistry and Trace Evidence > Emerging Technologies and Methods Forensic Medicine > Imaging Modalities

Yttrium orthovanadates phosphors as up-conversion luminescent markers for gunshot residue identification

In this work, yttrium orthovanadate phosphors doped with Er3+ and Yb3+ (YVO4: Er3+, Yb3+) were synthetized by the combustion method. After a post-synthesis heat treatment (1100 °C for 6 h), samples were highly crystalline, with only the tetragonal zircon phase remaining. Additionally, all samples presented promising down and up conversion properties, exhibiting a strong green luminescence when excited by either UV or IR radiation. The up-conversion process involved the absorption of two-photons, with the intensity of the Er3+ transitions (2H11/2–4I15/2, 4S3/2–4I15/2 and 4F9/2–4I15/2) heightened with the Yb3+ content. The co-doped orthovanadate samples were introduced into 9 mm non-toxic ammunition (NTA) for evaluation as luminescent markers for gunshot residues (GSR). After shots with marked ammunition were fired, these phosphors enabled the visual detection of luminescent GSR (LGSR) on the shooter, firearm and firing place, facilitating an analysis of the simulated crime scene. These residues also presented a chemical signature that enabled their identification as LGSR. Besides, the down and up conversion properties observed in the residues provide an additional security feature for the unequivocal characterization of the LGSR.

Analysis of gunshot residues from nontoxic ammunition: a contribution to health and environmental analysis

This study’s aim was to determine the presence, as well as to evaluate the health and environmental impacts, of chemical elements from firearm shots during shooter practice at outdoor shooting ranges, both in the environment and on the shooters’ hands. Two high-precision devices were used for measuring suspended particles that are released during discharge of Taurus PT 100 .40 caliber pistols. The analysis of collected data allowed the identification of specific distribution patterns of samples that were adsorbed. Moreover, samples were collected from the opisthenar area of the hand to investigate both the occurrence and deposition of particles and chemical elements through scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). The results indicate that copper, lead, and zinc concentration profiles will be able to delimit and reveal more precise details regarding shots made with nontoxic ammunition (NTA). In particular, the residual graphic analysis indicated that the majority of metal deposited in the shooter's hand is zinc. Further, the metals barium and lead also were detected. Due to the exposure to these elements, it could be concluded that engineering controls and administrative management should be sought in order to avoid human overexposure and environmental release of these airborne toxic metals.

Chromatographic Analysis of Byproducts from a Non-Toxic Ammunition and a Marked Ammunition: An Assessment of Toxicity

One way to access the toxicity of a fired ammunition is by analyzing the byproducts generated by shooting. This work has analyzed compounds produced by firing non-toxic ammunition (NTA) by Gas Chromatography-Mass Spectrometry (GC-MS). In addition to standard NTA, NTA containing luminescent markers were also analyzed. Luminescent markers have been shown to be an excellent tool in the identification of Gunshot Residues (GSR) produced from NTA. As these markers are designed to tag NTA, they must not produce toxic byproducts. In this work, we focused on identification of volatile products that can be inhaled by shooter when firing and can represents risk to their heath by acute and chronic exposition. For the NTA ammunition several toxic compounds, such as benzonitrile and naphthalene were found. They were related to de degradation of explosives, sensitizers, stabilizers, and other materials added to the gunpowder, indicating possible toxicity by shooters’ long exposure. Moreover, as some of the compounds found are classified as GSR indicators, the used methodology could be adapted for GSR identification. Besides the compounds identified in NTA samples, in marked samples, pyridine and benzene were identified. Pyridine was provided by dipicolinic acid and benzene was provided by trimesic or terephthalic acid, all used as binder in the structures of the markers. However, it can be concluded that the possible toxicity of the NTA is mainly not altered by the presence of the markers because of the small amount of marker added to ammunition and because only a small part of the marker is degraded, requiring an unreal number of shots to produce some acute effect.

Application of luminescent markers to ammunition encoding in forensic routine using a Video Spectral Comparator (VSC)

Gunshot residue (GSR) is an important part of forensic evidence. The implementation of non-toxic ammunition (NTA) hampers GSR characterization by conventional techniques. As an alternative, the incorporation of luminescent markers to ammunition has been proposed. The possibility of aggregation of different markers into gunpowder enables the possibility of ammunition encoding. Thus, the main objective of this study was to differentiate and evaluate for forensic use two previously studied ammunition markers based on europium ion (Eu(BTC) and Eu(BDC)) by employing a Video Spectral Comparator (VSC), well-known and widely used in scientific police laboratories. Chemometric methods demonstrated an unequivocal identification of the LGSR tested samples resulting in a 100% correct classification rating using Partial Least Squares Discriminant Analysis (PLS-DA).

Characterisation of gunshot residues from non-toxic ammunition and their persistence on the shooter's hands.

The aim of this work was to characterise three non-toxic ammunition (NTA) from the GECO and Fiocchi brands, which are available in the Italian market. Characterisation was carried out by considering both the elemental chemical composition and morphology, using scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM-EDS). Particles were collected from both the cartridge cases and the shooters' hands after shooting tests. Six volunteers fired two shots for each ammunition. Several elements, such as aluminium, potassium, silicon, sulphur, titanium and zinc were found in gunshot residue (GSR) particles from different ammunition. We also studied the persistence of these types of GSR on the hands of the shooters in a range between 1 and 6h after shooting. The GSR particles from the three NTA tested were found on the hands of shooters until 6h after the shots. The characterisations undertaken in this work will be useful for specialists in forensic science and legal medicine to evaluate trace evidence from these new NTA in casework, as such formulations are in growth.

Identification of Luminescent Markers for Gunshot Residues: Fluorescence, Raman Spectroscopy, and Chemometrics

Gunshot residue (GSR) is an evidence of major importance in firearm-related crimes. The recent introduction of nontoxic ammunition has made impossible the characterization of GSR particles by the current methods employed by forensic experts. To overcome this drawback, the introduction of luminescent markers was proposed, allowing on-site visual detection of luminescent gunshot residue (LGSR) at the crime scene. Three different luminescent markers coordinated with europium for specific and selective encoding of ammunition have been proposed. To promote a variety of versatile tools for GSR analysis, spectroscopic techniques combined with chemometric methods can be applied to achieve a reliable, fast, and nondestructive means to identify LGSR and discriminate among the different markers. Luminescence (emission and excitation), normal, and resonance Raman spectroscopies associated with principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were evaluated. The classification model using the complementary information on emission and excitation spectra, a.k.a. data fusion, provided a 100% correct classification for all markers. A comprehensive study has been developed to show that the insertion of luminescent markers enables not only the easy localization of GSR residues but also the possibility of ammunition encoding through the use of multivariate classification methods.

Transitioning to non-toxic ammunition: Making change happen.

If the multiple negative health impacts associated with lead ammunition are to be mitigated, a transition to the non-toxic alternatives is needed. This paper aims to map out the pathways to such a transition via a modification of Kotter's eight step theory of change, identifying key stakeholders, exploring options for those of us advocating change and the relationships between policy and persuasion. The focus is primarily on the UK, but it is of direct relevance to the rest of Europe and beyond. The theory of change model involves (1) creating urgency, (2) building coalitions, (3) creating a vision for change, (4) communicating that vision, (5) removing barriers to enable action, (6) creating short-term or geospatial wins, (7) building on the change and (8) embedding change in culture and regulation. The paper reflects on good progress to date in initial steps, but throughout subsequent steps creative engagement and other disciplines which appreciate the human dimensions such as mediation and psychology of behaviour change have been lacking. Although significant barriers remain for Step 5, the paper identifies the central vision of sustainability of hunting as a shared value around which most stakeholders can engage. The paper concludes that, given the growing momentum surrounding this issue in recent years, the phasing out of lead ammunition is at a tipping point.

Lead pollution from hunting ammunition in Argentina and current state of lead shot replacement efforts.

Waterfowl hunting in Argentina is a profitable industry that attracts hunters from all over the world. Most hunting occurs as high-end hunting tourism, through which registered outfitters service predominantly foreign clients on private lands. Lead pollution from hunting ammunition is increasingly recognized as a significant local problem, impacting wildlife, aquatic and terrestrial habitats, and extending to vulnerable human rural communities. Regulatory frameworks that restrict lead shot use are a budding success story but remain challenged by their constrained geographic range and limited compliance rooted in unavailable nontoxic ammunition. Changes in hunting practices in Argentina are long overdue.

Evaluation of the sub-surface morphology and composition of gunshot residue using focussed ion beam analysis

Recent work in the forensic analysis of Gunshot residues (GSR) has suggested that the sub-surface or internal composition and morphology of these residues be explored. A particular area of interest is in heavy metal free, or non-toxic ammunition, which are becoming more frequently encountered in the marketplace. As the formulation of the primer compound changes the conditions of the firearm discharge, there is the possibility that different primer formulations may result in the formation of different GSR particles with distinct internal morphologies and compositions. To that end, the internal morphology and composition of GSR particles may provide additional information that could be useful in the investigation of firearms crime.This research investigated the internal morphology of GSR originating from a variety of different ammunition products. Both traditional three-component primed ammunition, and a selection of heavy metal free and non-toxic alternatives were considered. Particles were identified using SEM–EDS, before being cross-sectioned using a focussed ion beam (FIB) instrument. The FIB-sectioned particles were then re-acquired and mapped using SEM–EDS, to assess both internal morphology and composition.Particles observed in this study presented distinct morphological and compositional features at the sub-particle level that may provide an indication of the primer formulation from which they originated. That said, further investigation of a variety of samples should be undertaken to verify the consistency of these features, or any deviations that may be observed based on primer type. However, these results indicate that there may be promise in obtaining additional detail from sub-particle morphology and composition.

Ammunition encoding by means of co-doped luminescent markers

In forensics, the identification of gunshot residues (GSR) is a crucial point in firearm crime investigations. However, there is a lack of analytical methodologies to characterize the residues produced by non-toxic ammunition (NTA). To overcome this drawback, researchers have proposed the introduction of luminescent and chemical markers into ammunition. Luminescent markers, besides overcoming problems of NTA analysis, aid to identify and collect GSR by direct visualization of luminescent residues under UV radiation. Furthermore, the development of new markers with unique compositions has opened new perspectives about encoding ammunition. In this work, we propose the use of eight co-doped lanthanide metal-organic frameworks (Ln-MOF) [Y1−XLnX(BTC)] (wherein BTC = trimesic acid) containing discrete concentration levels of Eu3+, Tb3+, Sm3+ and/or Yb3+ ions, as chemical barcodes for ammunition. To assess the method efficiency, we performed blind tests in which neither the shooters and the analyst had knowledge about the marker present in each cartridge that was fired. After shots, the residues were collected and analyzed by scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and video spectral comparator (VSC) to identify the marker used. As result, all of the markers were correctly identified. In addition, correlation between the residues collected at different locations (as hands, firearm and shooting area) was possible. Therefore, the encoding method proposed proved to be a powerful analytical tool for firearm crime investigations, providing a level of information that cannot be achieved with the current methodologies.

New luminescent lanthanide-based coordination compounds: Synthesis, studies of optical properties and application as marker for gunshot residues

New lanthanide-based luminescent coordination compounds containing thiabendazole (TBZ) as ligand were synthesized. Elemental analysis, mass spectrometry, thermogravimetric analysis and infrared spectroscopy were important for structural elucidation, providing the following chemical structures: [Eu(TBZ)2(NO3)3]·H2O and [Tb(TBZ)2(NO3)3]·H2O, called as EuTBZ and TbTBZ, respectively. Photoluminescence spectroscopy was also performed. EuTBZ and TbTBZ emitted characteristic red (618 nm) and green (542 nm) light, corresponding to chromaticity coordinates (0.57; 0.40) and (0.23; 0.54), respectively. Emission quantum efficiency of EuTBZ 5D0 was 57%. TbTBZ showed higher quantum yield than EuTBZ, 35% against 0.2%. Forensic tests were performed using TbTBZ as a marker in the 9 mm ammunition allowing visualizing luminescent gunshot residues (GSR) on the target, weapon and cartridge. It can help experts in analyzing crime scene, directing GSR collection and providing an optical and chemical signature to GSR derived from non-toxic ammunition.

Use of luminescent gunshot residues markers in forensic context—Part II

Gunshot residues (GSR) are important physical evidence in firearm-related crimes. Recently developed non-toxic ammunition, however, requires a new methodology for its characterization. To overcome this drawback, the introduction of noncommercial luminescent markers in ammunition was proposed. These markers, synthesized and added to the gunpowder, presented as a versatile tool for GSR analysis, since they require UV radiation alone to visualize the luminescent GSR (LGSR). This has opened up new perspectives for understanding GSR behavior at a crime scene. This work aims to expand previous studies performed with the luminescent markers in forensic contexts, exploring four different important aspects related to GSR behavior. Using LGSR amount/dispersion and a series of blind tests with marked ammunition, we tried to (1) identify the shooter position; (2) estimate the shooting distance; (3) evaluate the influence of the pistol type on the LGSR distribution on the shooter’s hands and guns; and (4) study the transference of LGSR by a chain of handshaking. For this purpose, a portable UV lamp (λ=254nm) and/or techniques such as video spectral comparator (VSC) and scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDS) were used to visualize and analyze the residues. As a result, the observation of the LGSR enabled accurate determination of the shooter position and the firing distance without any chemicals. Besides, the LGSR were visualized on different kinds of pistols, regardless of firing mechanism. And finally, this study evidenced transference of residues from shaking hands with the shooter, which should be carefully considered when interpreting the results of a GSR analysis.

Short wave infrared chemical imaging as future tool for analysing gunshot residues patterns in targets

This work used chemical imaging in the short-wave infrared region for analysing gunshot residues (GSR) patterns in cotton fabric targets shot with conventional and non-toxic ammunition. It presents a non-destructive, non-toxic, highly visual and hiperspectral-based approach. The method was based on classical least squares regression, and was tested with the ammunition propellants and their standard components’ spectra. The propellants’ spectra were satisfactorily used (R2 >0.966, and CorrCoef >0.982) for identifying the GSR irrespective of the type of ammunition used for the shooting. In a more versatile approach, nitrocellulose, the main component in the ammunition propellants, resulted an excellent standard for identifying GSR patterns (R2>0.842, and CorrCoef >0.908). In this case, the propellants’ stabilizers (diphenilamine and centralite), and its nitrated derivatives as well as dinitrotoluene, showed also high spectral activity. Therefore, they could be recommended as complementary standards for confirming the GSR identification. These findings establish the proof of concept for a science-based evidence useful to support expert reports and final court rulings. This approach for obtaining GSR patterns can be an excellent alternative to the current and traditional chemical methods, which are based in presumptive and invasive colour tests.

Application of the Metal-Organic Framework [Eu(BTC)] as a Luminescent Marker for Gunshot Residues: A Synthesis, Characterization, and Toxicity Study.

The 3D metal-organic framework (MOF) [Eu(BTC)] (where BTC = trimesic acid) was synthesized in 20 min by a microwave-assisted hydrothermal method with a yield of 89%. A structural and spectroscopic study, performed by X-ray diffraction, thermogravimetry, and photoluminescence spectroscopy, showed that this framework has high crystallinity, thermal stability, and luminescence. This MOF had a red-orange luminescence when excited with ultraviolet (UV) radiation (λ = 254 nm) and a high potential for use as a luminescent marker for gunshot residues (GSR). When added to 9 mm nontoxic ammunition, it greatly improved quality of the crime scene investigation, allowing for direct visualization of the luminescent GSR on the shooter's hand and firearm and at the firing range using only a portable UV lamp. The marked luminescent GSR was easily collected and characterized by nondestructive techniques, including with a Video Spectral Comparator and scanning electron microscopy/energy-dispersive spectroscopy, wherein the presence of Eu3+ ions was confirmed. Furthermore, the oral acute toxicity of this MOF was assessed in adult female Wistar rats using the Organisation for Economic Cooperation and Development 423 guidelines. This study classified the MOF [Eu(BTC)] in a less toxic Globally Harmonized System category (category 5), with a LD50 (lethal dose) of 5000 mg/kg, ensuring a wide security range for its application.

Elemental Characterization and Discrimination of Nontoxic Ammunition Using Scanning Electron Microscopy with Energy Dispersive X-Ray Analysis and Principal Components Analysis.

Concerns over the toxic by-products produced by traditional ammunition have led to an increase in popularity of nontoxic ammunition. In this work, the chemical composition of six brands of nontoxic ammunition was investigated and compared to that of a road flare, which served as an environmental source with similar composition. Five rounds of each brand were fired while a further five were disassembled and the primer alone was fired. Particles collected from all samples, including the road flare, were analyzed by scanning electron microscopy with energy dispersive X-ray analysis. Common elements among the different ammunition brands included aluminum, potassium, silicon, calcium, and strontium. Spectra were then subjected to principal components analysis in which association of the primer to the intact ammunition sample was generally possible, with distinction among brands and from the road flare sample. Further, PCA loadings plots indicated the elements responsible for the association and discrimination observed.

Fast Analysis of Complete Macroscopic Gunshot Residues on Substrates Using Raman Imaging.

Raman spectroscopy has emerged as a viable technique for the organic analysis of gunshot residues (GSRs), offering additional information to the well-established analysis using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). In this article, a Raman imaging system with an electron-multiplying coupled-charged device (EMCCD) camera was used to analyze complete GSR particles from both conventional and nontoxic ammunition fired at different cloth targets. The same cloths were then stained with blood to mimic real evidence and measured. The direct analysis using Raman imaging of the GSR particles collected with the stubs used for SEM-EDX analysis (the frequent method used for GSR collection) was evaluated. Multivariate curve-resolution and chemical-mapping methods were applied to the spectroscopic data to identify and highlight the signal corresponding to the GSR particles and differentiate them from the substrates. It was confirmed that both measurement approaches (on the targets and the stubs) could be used for the identification of GSR particles, even under unfavorable conditions such as the presence of blood. The results obtained demonstrate the huge potential of Raman imaging for the fast analysis of complete GSR particles and prove its complementary usefulness in the analysis of the stubs used by the well-established SEM-EDX technique.

High risk of lead contamination for scavengers in an area with high moose hunting success.

Top predators and scavengers are vulnerable to pollutants, particularly those accumulated along the food chain. Lead accumulation can induce severe disorders and alter survival both in mammals (including humans) and in birds. A potential source of lead poisoning in wild animals, and especially in scavengers, results from the consumption of ammunition residues in the tissues of big game killed by hunters. For two consecutive years we quantified the level lead exposure in individuals of a sentinel scavenger species, the common raven (Corvus corax), captured during the moose (Alces alces) hunting season in eastern Quebec, Canada. The source of the lead contamination was also determined using stable isotope analyses. Finally, we identified the different scavenger species that could potentially be exposed to lead by installing automatic cameras targeting moose gut piles. Blood lead concentration in ravens increased over time, indicating lead accumulation over the moose-hunting season. Using a contamination threshold of 100 µg.L−1, more than 50% of individuals were lead-contaminated during the moose hunting period. Lead concentration was twice as high in one year compared to the other, matching the number of rifle-shot moose in the area. Non-contaminated birds exhibited no ammunition isotope signatures. The isotope signature of the lead detected in contaminated ravens tended towards the signature from lead ammunition. We also found that black bears (Ursus americanus), golden eagles and bald eagles (Aquila chrysaetos and Haliaeetus leucocephalus, two species of conservation concern) scavenged heavily on moose viscera left by hunters. Our unequivocal results agree with other studies and further motivate the use of non-toxic ammunition for big game hunting.