Elemental Analysis of Glass by SEM-EDS, uXRF, LIBS and LA-ICP-MS

• NCJ Number: 240592
• Author(s): Jose Almirall; Ben Naes; Erica Cahoon; Tatiana Trejos
• Date Published: April 2011
• Length: 88 pages
• Grant Number(s): 2005-IJ-CX-K069
• Agencies: NIJ-Sponsored
• Publication Type: Report (Study/Research)

Annotation

This study compared the proficiency of the following techniques in performing an elemental analysis of glass: laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS); scanning electron microscopy-energy dispersive spectrometry (SEM-EDS); micro X-Ray fluorescence spectrometry (uXRF); and laser induced breakdown spectroscopy (LIBS).

Abstract

The testing found that LIBS provides excellent discrimination potential for a glass set that consists of 41 automotive fragments recovered from 14 vehicles. When the discrimination power of LIBS was compared to two of the leading elemental analysis techniques, uXRF and LA-ICP-MS, all methods produced greater than 99 percent discrimination, and the pairs found indistinguishable were correlated across the analytical methods. Included in this research was an extensive data analysis method developed by the authors to minimize false inclusion and eliminate false exclusions for LIBS spectral comparisons. This resulted in the recommendations of 10 ratios for use in glass discrimination by LIBS. The researchers concluded that LIBS - with its rapid analyses, lower cost, and reduced complexity - can provide a viable alternative to uXRF and LA-ICP-MS in forensic laboratories. The current project, along with other research, indicates that SEM-EDS should only be used either for classification between glass types or for the exclusion of an association when the glass samples have an obvious compositional difference. This is due to the limited utility of SEM-EDS in differentiating between different glass samples due to poor sensitivity and the fact that SEM-EDS is a qualitative-analysis method that produces differences in analytical results that depends on sample morphology. The second part of this project resulted in the optimization of the LIBS method for glass examination and the dissemination of this information through scientific presentations at national and international meetings and during teaching workshops. 22 figures, 16 tables, 63 references, and appended information on the dissemination of this research