Authors: Waleska Castro Tatiana Trejos Benjamin Naes José R Almirall
Publish Date: 2008/08/05
Volume: 392, Issue: 4, Pages: 663-672
Abstract
Forensic laboratories routinely conduct analysis of glass fragments to determine whether or not there is an association between a fragments recovered from a crime scene or from a suspect to a particular source of origin The physical and optical refractive index properties of the fragments are compared and if a “match” between two or more fragments is found further elemental analysis can be performed to enhance the strength of the association A range of spectroscopic techniques has been used for elemental analysis of this kind of evidence including inductively coupled plasma mass spectrometry ICPMS Because of its excellent sensitivity precision and accuracy several studies have found that ICPMS methods dissolution and laserablation provide the best discrimination between glass fragments originating from different sources Nevertheless standard unitresolution ICPMS instruments suffer from polyatomic interferences including 40Ar16O+ 40Ar16O1H+ and refractory oxide 40Ca16O+ that compromise measurements of trace levels of Fe56+ and Fe57+ for example This is a drawback in the analysis of glass fragments because iron has been previously identified as a good discriminating element Currently several techniques are available that enable reduction of such interferences However there are no data comparing detection limits of iron in glass using those techniques The aim of this study was to compare the analytical performance of highresolution sector field inductively coupled plasma mass spectrometry HRSFICPMS and quadrupole ICPMS equipped with a dynamic reaction cell DRCICPMS for the detection of iron in glass in terms of accuracy precision and method detection limits MDLs Analyses were conducted using conventional aciddigestion and laserablation methods For laserablation analyses carrier gases were compared to assess the effect on detection limits in the detection of iron isotopes Iron polyatomic interferences were reduced or resolved by using a dynamic reaction cell and highresolution ICPMS MDLs as low as 003 μg g−1 and 014 μg g−1 were achieved in laserablation and solutionbased analyses respectively Use of helium as carrier gas improved detection limits for both iron isotopes in mediumresolution HRSFICPMS and in DRCICPMSThis work was supported by the National Institute of Justice NIJ grant 2005IJCXK069 The HRSFICPMS was acquired with National Science Foundation NSF Major Research Instrumentation MRI award 0420874 to Florida International University The Florida International University and the FIU Dissertation Year Fellowship are also acknowledged
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