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Human exposure to organic gunshot residues is a largely under researched topic in environmental and occupational health. This study aimed to examine how the components of a complex liquid blend affect the permeation behavior of its constituents. In the initial study, Hoppes No. 9 Gun Bore Cleaner, a firearm cleaning solvent, was chosen to test two types of disposable nitrile gloves from Kimberly-Clark’s Kimtech Science: the thinnest (Lavender) and thickest (Blue). Testing was conducted using the 1-inch diameter closed-loop ASTM F739 cell at 35℃ without recirculation with n-decane collection, and subsequent analysis via capillary gas chromatography-mass spectrometry to quantify the permeated compounds. Results showed that the thicker Blue glove resisted Hoppe’s permeation more than the thinner Lavender glove. The Lavender glove permeated 3.2 times more mass at 60 minutes despite having the same standardized breakthrough times (7.5 ± 2.5 min). Unexpectedly, the kerosene fraction permeated at a much higher rate than anticipated, appearing at the standardized breakthrough time for Hoppe’s, contrary to the Kimberly-Clark chemical resistance guide's listing for Sterling disposable nitrile glove material. Notably, components reported by the glove manufacturer to quickly permeate nitrile material, like ethanol, did not permeate slower than expected, hinting at a possible carrier function. A semiquantitative risk assessment confirmed the inadequacy of both gloves, suggesting that individuals using personal protective equipment may not receive the anticipated resistance to chemical permeation when dealing with complex mixtures, thus heightening exposure risk. Further research is necessary to develop improved glove testing measures to ensure worker safety and health.Additionally, this research examined how methyl centralite and ethyl centralite, two major gunshot residue components, simulated gunshot residues when permeating disposable nitrile glove material in three different

Understanding the prevalence of Organic Gunshot Residue (OGSR) particles in a non-shooting environment can provide useful information in forensic investigations. Previous studies have shown that certain OGSR compounds are widely used in various occupational sources. This research investigated the prevalence of OGSR in various non-shooting occupational sources. Samples were collected from the hands of 90 volunteers using polyester swabs and deionized water. A total of 119 qualified samples were analyzed for the presence of 2,6 dinitrotoluene (2, 6- DNT), trinitroglycerin (TNG), and ethyl centralite (EC) using Gas Chromatography-Mass Spectrometry (GC-MS). This research determined that of those 119 samples: 100 samples contained 2, 6- DNT, 25 samples contained EC at a threshold concentration of 0.5 ug/mL or above, and no sample contained TNG at a threshold concentration of 25 ug/mL or above. According to previous studies, the presence of TNG and EC as a pair is considered characteristic of OGSR; therefore, these findings were not characteristic of OGSR. Furthermore, these results strengthen the likelihood that certain OGSR compounds, if found in pairs, are indicative of a discharge of a firearm. The use of this knowledge in conjunction with the traditional analysis of GSR can reduce the risk of false negative results. With the aid of future studies to incorporate known shooter samples to assess the threshold levels of these compounds in real life scenarios, OGSR analysis can ultimately strengthen the probative results of forensic GSR analysis in the criminal justice system.

We study the possibility of evaluating the elemental composition of automotive (vehicle) coating paints and determining the gunshot residue from 5.6 mm bullets of a small-caliber gun using the EDXRF technique. An Elvax EDXRF spectrometer, consisting of a Si-PIN detector with a resolution of 200 eV for MnKα radiation with energy of 5.9 keV and a mini X-ray tube with Rh anode, was used. Results of the study showed that the number of shots was directly correlated to the relative intensity of barium and lead on the gunshot target, and the distance of the shooting could be determined using chemical elements intensities, such as Pb, S, Ba and Cu intensities, from the gunshot residue. In the case of automotive paints, the elements identified in the samples were Ca, Ti, Fe, Cu, Cl, Zn, Cr and Pb, and the EDXRF technique could be used for the identification of the different cars by the paint coating samples from the crashed car. This work was the first study which used the EDXRF analysis for automotive paints in Mongolia., Исследована возможность оценки элементного состава автомобильных лакокрасочных покрытий и определения химического состава остатков после выстрела из пистолета с пулями 5.6 мм с использованием технологии энергодисперсионного рентгено-флуоресцентного анализа (ЭДРФА). Использован спектрометр Elvax EDXRF, состоящий из Si-PIN-детектора с разрешением 200 эВ для излучения MnKα c энергией 5.9 кэВ и мини-рентгеновской трубки с Rh-анодом. Для обработки спектра использовано программное обеспечение ELVAX. Результаты исследований показали, что количество выстрелов коррелирует с относительной интенсивностью излучения линий бария и свинца на огнестрельной мишени, а расстояние от огнестрельного оружия до цели можно определить, используя интенсивности некоторых химических элементов остатков выстрелов из огнестрельного оружия, таких как Pb, S, Ba и Cu. В случае автомобильных красок элементами, идентифицированными в образцах, оказались Ca, Ti, Fe, Cu, Cl, Zn, Cr и Pb, а метод ЭДРФА может использоваться для распознавания различных автомобилей по образцам лакокрасочного покрытия из разбитого автомобиля. Эта работа является первым исследованием, в котором использовался анализ ЭДРФА для автомобильных красок в Монголии.

This master thesis investigates the use of chemically exfoliated graphene, CdSe/CdS/ZnS quantum dots and graphene quantum dots for fluorescence based detection of gunshot residue and explosives. Specifically, nitroglycerine is chosen as the target substance in gunshot residue and the nitroaromatic compounds trinitrotoluene and dinitrotoluene are chosen as target explosives. The experimental work is divided into three part were the first one is an investigation of the quenching of semiconductor quantum dot fluorescence by graphene. The results show that graphene is an efficient quencher, and it is probable that quenching takes place without the fluorescing and quenching agents being in contacts, through either Förster resonance energy transfer or nanometal surface energy transfer. The second part is a study of how nitroaromatic molecules quench the fluorescence from graphene quantum dots. The results indicate that the solvent of the nitroaromatics passivates the functional groups which reduces the quenching efficiency. Nevertheless, it is concluded that the nitroaromatics quench the fluorescence. It is possible that the quenching mechanism is photoinduced charge transfer. The last part of the experimental work investigates the influence of nitroaromatics on the graphene and semiconductor quantum dot hybrid from the first part. It is shown that nitroaromatics further quench the fluorescence of the quantum dots in the hybrid structure, possibly by photoinduced charge transfer or by reacting with the surface coating of the quantum dots and thereby introducing de-excitation through surface states.

The capillary microextraction of volatiles (CMV) device was equipped with a novel Peltier cooler to investigate cryofocused extraction of organic gunshot residue (OGSR) for the first time. Prior research demonstrated the CMV’s capabilities for detecting nitroglycerin, 2,4-dinitrotoluene, diphenylamine, and ethyl centralite on shooters’ hands via gas chromatography-mass spectrometry. Further method development increased the recoveries of these four target compounds with an optimal 20-minute equilibrium time at 80˚C followed by extracting 3 L at a 1 L/min flow rate. The Cryo-CMV was evaluated for detection of semi-volatile OGSR compounds. The unique challenges presented with sampling of semi-volatiles were overcome by sample heating, applying high (>1 L/min) sampling flow rates and heating the transfer line between the container and cooled CMV. Cryofocusing at -10˚C provided increased recoveries for smokeless powders and OGSR compounds and therefore demonstrates excellent potential for other forensic applications with analysis of VOCs from fire debris and illicit drugs.

Gunshot residue (GSR) is the term used to describe the particles originating from different parts of the firearm and ammunition during the discharge. A fast and practical field tool to detect the presence of GSR can assist law enforcement in the accurate identification of subjects. A novel field sampling device is presented for the first time for the fast detection and quantitation of volatile organic compounds (VOCs). The capillary microextraction of volatiles (CMV) is a headspace sampling technique that provides fast results (< 2 min. sampling time) and is reported as a versatile and high-efficiency sampling tool. The CMV device can be coupled to a Gas Chromatography-Mass Spectrometry (GC-MS) instrument by installation of a thermal separation probe in the injection port of the GC. An analytical method using the CMV device was developed for the detection of 17 compounds commonly found in polluted environments. The acceptability of the CMV as a field sampling method for the detection of VOCs is demonstrated by following the criteria established by the Environmental Protection Agency (EPA) compendium method TO-17. The CMV device was used, for the first time, for the detection of VOCs on swabs from the hands of shooters, and non-shooters and spent cartridges from different types of ammunition (i.e., pistol, rifle, and shotgun). The proposed method consists in the headspace extraction of VOCs in smokeless powders present in the propellant of ammunition. The sensitivity of this method was demonstrated with method detection limits (MDLs) 4-26 ng for diphenylamine (DPA), nitroglycerine (NG), 2,4-dinitrotoluene (2,4-DNT), and ethyl centralite (EC). In addition, a fast method was developed for the detection of the inorganic components (i.e., Ba, Pb, and Sb) characteristic of GSR presence by Laser Induced Breakdown Spectroscopy (LIBS). Advantages of LIBS include fast analysis (~ 12 seconds per sample) and good sensitivity, with expected MDLs in the range of 0.1-20 ng for tar

The separation and quantification of chemical substances in a wide variety of complex matrices is a significant analytical challenge to the forensic chemist. Capillary electrophoresis (CE) is attractive to the forensic chemist as it has the potential to provide exceptional separating power in combination with rapid analysis times and high mass sensitivities. It is also economical of both reagents and sample. Owing to the variety of separation modes possible (electrophoretic, electrokinetic, chromatography-like, etc.) and the detection systems available (UV–visible absorbance, luminescence, and mass spectrometry are all available commercially), it is applicable to the determination of a wide variety of chemical substances including inorganic ions, small organic molecules, chiral compounds, macromolecules, and intact viruses and cells. This article provides an overview of the application of CE to forensic chemical analysis, illustrated with recent examples.

Lonsdale, W., Wajrak, M., Ridgway, S.N. (2015). Onsite measurement of lead in gunshot residues using linear sweep voltammetry. Modern Environmental Science and Engineering. 1(4), 192-195. Available here