NUMBER 77 Title : The Analysis of Lead Bullet Samples

The utility of multielement techniques for forensic analysis has been well documented in a recent article [1]. Typical analytical methods used for qualitative analysis include x-ray fluorescence (XRF), and emission spectroscopy (ES). Until the 1980's, neutron activation analysis (NAA) was the definitive method used for quantitative elemental analysis. However this technique has limited applicability, it is slow, expensive, and requires special facilities. NAA cannot be used to analyze Pb and results for other elements may be ambiguous. This was demonstrated by the NAA bullet analysis from the Kennedy assassination [2]. Gunshot residues (GSR), products of firearm discharge, are commonly distributed on the hands of persons touching the gun when it was fired. These residues may also be found on the entrance and exit orifices from bullet penetration. Graphite furnace atomic absorption spectrometry (GFAAS) and NAA have commonly been used in the past to detect GSR on tissues, textiles, and hand swabs [3-9]. Lead, Ba, and Sb are common indicators of GSR. GFAAS requires a high degree of operator skill, the useful analytical range is very limited, it is prone to spectral interference (Na, interferes on the determination of Ba), it is a single element technique with poor sample throughput, and matrix modifiers are required that could prevent additional analysis on samples.