Evaluation of the possibility of differentiation between various types of ammunition by means of GSR examination with SEM±EDX method Zuzanna Brozek-Mucha a,* , Agnieszka Jankowicz b a The Institute of Forensic Research, Westerplatte 9, 31-033 Cracow, Poland b Faculty of Chemistry, The Jagiellonian University, Ingardena 3, 30-060 Cracow, Poland Received 5 December 2000; received in revised form 18 May 2001; accepted 23 May 2001 Abstract Gunshot residues originating from six types of pistol ammunition were studied. Six persons who normally have no contact with weapons ®red three times, each person from a different pistol. Samples of gunshot residues were collected from the shooters' hands using aluminium stubs with black carbon adhesive tabs and subjected to examinations of their morphology and elemental content by means of a scanning electron microscope with an energy dispersive X-ray spectrometer in an automatic manner. In a comparative study of the samples, only primer residues were taken into account. The frequency of occurrence of particles representing a certain chemical class against the total number of detected particles was expressed as a percentage. Mutual relations between the frequencies of occurrence of the residues of particular chemical content were found to be different for most of the studied ammunition types using a non-statistical approach Ð and by means of non-parametric statistical methods R-Spearman and t-Kendall correlation coef®cients), it was possible to differentiate one ammunition type from each of the other ammunition types examined. The performed examinations have revealed some differences in the frequencies of occurrence of certain chemical classes of primer residues, observed for various types of ammunition. These differences could constitute a valuable contribution to group identi®cations of ammunition made on the basis of physical and chemical examinations of gunshot residues. # 2001 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Gunshot residues GSR); Cartridge discharge residues CDR); SEM±EDX; Non-parametric statistical methods; Wilcoxon sum rank test; Rank correlation coef®cients: R-Spearman and t-Kendall 1. Introduction Physical and chemical investigations of ®rearm discharge residues are nowadays performed routinely in order to solve a number of forensic problems such as identi®cation of gunshot wounds together with establishing of the entrance and exit [1]; estimation of the time since discharge of a ®rearm [2,3]; distribution of GSR at the crime scene; estimation of shooting distance [4,5]; and establishing whether a person has ®red a gun [6]. Sensitive analytical methods are required for the iden- ti®cation of inorganic gunshot residues that are usually present in very small quantities on a substrate. The following methods have been utilised for this purpose: atomic absorp- tion spectroscopy AAS), neutron activating analysis NAA) [7], X-ray ¯uorescence spectrometry XRF), inductively coupled plasma mass spectrometry ICP-MS) [8]. However, scanning electron microscopy with energy dispersive X-ray spectrometry SEM±EDX) was recognised as the most speci®c method. This method enables an expert to simulta- neously observe the characteristic morphology of a GSR and check its elemental content without prior damage of the object. The SEM±EDX method is, for this reason, enjoying growing popularity in investigations of this kind of evidence in forensic laboratories [9]. Particles detected with this method are classi®ed on the basis of their elemental conte- nts [10±14]. It has been established from empirical studies that in the case of lead ammunition only three-component Forensic Science International 123 2001) 39±47 * Corresponding author. Tel.: 48-12-422-87-55; fax: 48-12-422-38-50. E-mail address: zbrozek@ies.krakow.pl Z. Brozek-Mucha). 0379-0738/01/$ ± see front matter # 2001 Elsevier Science Ireland Ltd. All rights reserved. PII:S0379-073801)00518-7