A study of the effect of working parameters and validation of SEM/EDS method for determination of elemental composition of commonly encountered GSR samples in shooting events in Kosovo

Abstract

Reliability of forensic evidences for presence of inorganic gunshot residue (iGSR) on a given surface strongly depends on the performance of scanning electron microscopy/ energy dispersive X-ray spectrometry (SEM-EDS) method. This article presents the results from a study of the effect of SEM/EDS working parameters on the method performance and quality of iGSR data, as well as a development of a database of iGSR encountered in R Kosovo. The optimal working parameters of SEM/EDS were established by one-variable-at-a-time approach and the method was validated according to ASTM1588-10. The precision, trueness, and expanded uncertainty for PbBaSb particles were estimated and the method was assessed as a "fit for purpose" with a satisfactory performance (z-score < 2). Expended uncertainty of quantification of GSR particles estimated by single laboratory and quality control approach was 6% (k = 2).The validated SEM/EDS method was applied for identification of characteristic iGSR particles in samples from shooting events in Kosovo. The method was demonstrated to be capable of providing a legal proof for iGSR existence on a specific surface. The quality of the results was not influenced by the origin of iGSR. Five hundred fifty-five samples from 144 cases occurred during the last 3 years were analyzed and 14% rate of positive results was found.

Çeşitli İş Kollarında Çalışanların Ellerinden Elde Edilen Yanıltıcı Kalıntı Varlığının Araştırılması

“…The determination of the chemical and physical characteristics of firearm residues is crucial criminalistic evidence (Tahirukaj et al, 2021). For this purpose, two main analyses can be done intensively.…”

“…Many complicated processes are involved in the formation of these particles, which contain a variety of metal particles (aluminum, calcium, sulfur, copper, potassium, zinc, magnesium, sodium, and phosphorus, among others) as well as Sb, Ba, and Pb (Kara and Yalçinkaya, 2017). The determination of the chemical and physical characteristics of firearm residues is crucial criminalistic evidence (Tahirukaj et al, 2021). For this purpose, two main analyses can be done intensively.…”

“…In Table 5, the Sb&Ba&Pb particles numbers were 65671, 485 and 38 for "14a" "14b" and "15a", respectively. According to analysis of the standard sample , it was from the proficiency testing GSR 2005 PT by ENFSI GSR 2005 PT it was achieved by Tahirukaj et al, (2021) particles with diameter 0,5, 0,8, 1,2, and 2,4 µm were detected. The Total no of detected particles were 98, from 0,5 to 2,4 µm; and the standard deviation (SD) was 2.06.…”

“…Although these particles are found in GSR, people hands may be contaminated by Sb, Ba and Pb, depending on the working environment in different business lines (Costa et al, 2016). As a result, these three elements, particularly Sb, were given considerable attention in the study of criminal (Di Maio, 1999;Yüksel et al, 2016;Stamouli et al, 2021;Tahirukaj et al, 2021). It is known that Sb is used in some Pb alloys, as well as Sb, Ba and Pb components in the hands of people working in certain professions such as electrical installers and car mechanics (Romolo and Margot, 2001;Romolo et al, 2019) .…”

Assessment of Persistence of Gunshot Residues Produced by Firearms from Criminal Cases in the Republic of Kosovo

“…The applied SEM/EDS protocol and quality control procedures, after method validation, could influence the obtained data [10,11]. The working parameters of an SEM/EDS instrument should be studied and optimized for each instrument's and laboratory's needs [12,13]. Differences in laboratories across countries and different sample types can cause significant variability in results and should be taken into account when interpreting shooting events [4,14].…”