A method based on scanning laser ablation and inductively coupled plasma-mass spectrometry (SLA-ICPMS) and Raman micro-spectroscopy for the detection and identification of compounds consistent with gunshot residue particles (GSR) has been developed. The method has been applied to the characterization of particles resulting from the discharge of firearms using lead-free ammunition. Modified tape lifts were used to collect the inorganic and organic residues from skin surfaces in a single sample. Using SLA-ICPMS, aggregates related to the composition of the ammunition, such as Cu-Zn-Sn, Zr-Sr, Cu-Zn, Al-Ti, or Al-Sr-Zr were detected, but this composition is only consistent with GSR from lead-free ammunitions. Additional evidence was provided by micro-Raman spectroscopy, which identified the characteristic organic groups of the particles as centralite, diphenylamine or their nitrated derivatives, which are indicative of GSR.

Mass spectrometry imaging (MSI) using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been employed for the elemental bio-distribution and quantification of uranium (U) in histological tissue sections of rodent kidneys. Kidneys were immediately immersed into 4% paraformaldehyde (PFA) solution for 24 h, Tissue-Tek O.C.T. Compound embedded and stored at − 80°C until cutting in a cryostat, and mounted in gel-covered glass slides. In order to assure complete ablation of sample, sample preparation and laser conditions were carefully optimized. In this work, a new analytical methodology is presented for performing quantitative laser ablation analyses based on internal standard (thulium, Tm)-spiked gelatine (10% m/v) for correction of matrix effects, lack of tissue homogeneity, and instrumental drift. In parallel, matrix-matched laboratory standards, dosed at different concentrations of U, were prepared from a pool of rat kidneys. The quantitative images of cryosections revealed heterogeneous distribution of uranium within the renal tissue, because the cortical concentration was up to 120fold higher than the medullary concentration.

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Laburpena: Azken urteotan, su-armen erabilera nabarmen handitu da gure gizartean eta horrek tiro egin ondoren sortutako partikulen analisirako metodologia berriak garatzea ekarri du. Krimenaren gertalekuan tiro-aztarnak (gunshot residue, GSR) osatzen dituzten konposatuen detekzioak eta identifikazioak su-armen erabileraren ebidentzia fidagarria eskaintzen dute. Tiro-aztarnak erretako eta erre gabeko partikulen multzoa dira, munizioa erretzen denean sortutakoak eta su-armak berak, jaurtigaiak eta kartutxoak askatutako konposatuez osatuak. Tiro egin ostean, partikulak tiroa gertatu den tokiaren inguruan jalkitzen dira, baina, batez ere, tiratzailearen gorputzean (eskuak, sudurra eta ilea) eta arropetan. Gaur egun, GSR partikulen ohiko analisia konposatu ez-organikoen identifikazioan oinarritzen da. Konposatu organikoen azterketak (organic gunshot residues, OGSR) lagin baten froga-balioa indartu dezake. Hala ere, gutxi dira OGSRen dudarik gabeko identifikaziorako guztiz sentikorrak diren metodoak. Lan honetan, beraz, tiro-aztarnen lagin-biltzea eta analisirako teknika aipagarrienak laburbildu eta berrikusten dira. Hitz-gakoak:Auzitegiko zientzia, tiro-aztarna ez-organikoak (IGSR), tiro aztarna organikoak (OGSR), lagin-biltzea, metodo analitikoak. Abstract:In the last years, the use of firearms has increased considerably in our society which has raised the development of new analytical methodologies in order to detect the particles formed during shooting. The detection and identification of compounds consistent with gunshot residues (GSR) in a crime scene provides forensic evidence of the use of firearms. These particles are a set of burned and unburned particles formed as a result of the combustion process of ammunition and contain components expelled from the firearm itself, the projectile and the cartridge case. After the discharge, particles are deposited on all surfaces in the vicinity where the shot has taken place but mainly in shooter's body (hands, nose and hair) and clothing. Currently, conventional analysis of GRS is focused on inorganic components. The study of organic components may strengthen the probative value of a sample. However, only a few studies propose analytical methods sensitive enough to identify OGSR. The cur-