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In this paper we present the fundamentals for a protocol for optimizing isotopic determination of lead for comparison of man-made glass by use of laser ablation inductively coupled mass spectrometry (LA-ICP-MS). Comparison of objects in order to establish a possible common origin is relevant within different disciplines, such as forensic sciences and archaeometry. Measurement of isotope ratios (IR) of lead is a method widely used by geochemists in order to establish the origin and evolution of minerals and rocks. In archaeometry, lead isotopes are used to determine the provenance of artefacts. Lead isotope ratios have shown potential not only for provenance determination, but also for comparison of different objects. Laser ablation as a sample introduction method to inductively coupled plasma mass spectrometry (LA-ICP-MS) is an established method in the geosciences, where it is used both for concentration and isotope ratio analysis of solids, but has still not obtained the same position in forensic science and archaeometry. The elegance of laser ablation as a sample introduction system is due to the simplicity of sample preparation and high spatial resolution. This spatial resolution provides advantages over methods where the sample has to be dissolved or melted in larger amounts. In order to outline a suitable protocol for analysis of lead isotope ratios in glass by LA-ICP-MS, we have followed a threefold approach. Firstly, we describe the influence of laser conditions on the Pb-isotope ratios obtained for low-lead glasses such as SRM NIST 610-614. Secondly, we evaluate the influence of the selection of detectors (ion counters vs. Faraday detectors) on the reliability of the final result. Thirdly, we discuss the phenomenon of fractionation and instrumental mass discrimination for lead during analysis.

Lead isotopes have been widely used to assess the sources of Pb in the soil environment since lead isotopes ratios have a specific signature that allows us to use them as environmental tracers. However, some lead sources are difficult to be identified. This article contains the lead isotope data from soils and shot pellets collected in an abandoned shooting range (NW Spain). Twelve soil and three-shot pellet samples were randomly collected and analyzed using MC-ICP-MS. The isotope ratios are shown, and analyses proved that Pb originated predominantly from the used shot pellets. Contaminated soils exhibited an isotopic composition (206Pb/207Pb, 208Pb/204Pb, 206Pb/204Pb and 208Pb/206Pb) close to some shot pellets from different manufacturers. These results offer new, valuable data for other researchers working on lead contamination research and the identification sources of Pb for adjacent areas to shooting-range facilities and for wildlife ecotoxicology. Still, the use of several ammunitions derived from different sources, such as recycled Pb, showed that it is hard to identify the lead source and these kinds of facilities.