Elemental Analysis of Glass by SEM-EDS, (mu)XRF, LIBS and LA-ICP-MS.

摘要

The transfer of small quantities of materials has become an important yet underutilized type of evidence at many crime scenes including hit-and-run accidents and other violent crimes. Although the utility of trace elemental analyses and comparisons for glass and paint fragments by sophisticated methods such as laser ablation inductively coupled plasma (LA-ICP-MS) has been shown to offer a high degree of discrimination between different sources of these materials, the high expense and sophistication of this technique has limited the adoption of this technology by the typical forensic laboratory, although there are now approximately 5 forensic laboratories in the U.S. with LA-ICP-MS capabilities. This 4.5 year research effort included an original award in 2005 and a continuation award in 2009 and has expanded on the PIs previous research in elemental analysis of materials (DoD/TSWG, end date 12/2002 and NIJ, end date 7/2005) to conduct a thorough evaluation of a number of elemental analysis methods (SEM-EDS, uXRF, LIBS and LA-ICP-MS) and compare the discrimination power between the methods used in most forensic laboratories for glass analysis. The continuation of the original proposal evaluated the analytical parameters for the LIBS analysis with an aim to create a more standard method that can be used by the operational forensic laboratory. The continuation award further advanced the selection of a match criteria based on LIBS (and uXRF) results for use in routine casework situations. This work was proposed as many operational laboratories in the US are adopting an elemental analysis component for glass and other trace evidence and to assist these labs in the decisionmaking process.