Trace Evidence Analysis of Forensic Samples Using Inductively Coupled Plasma
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Authors
Huang, Lily
Date
Type
thesis
Language
eng
Keyword
ICP-OES , ICP-MS , Forensics
Alternative Title
Abstract
At many crime scenes, little evidence is left behind; thus, the more tools available for the analysis of minute samples, the better. For instance, trace elemental impurities are not regulated in many commercial materials and thus could be a unique identifier. One of the best techniques for multi-elemental trace analysis is inductively coupled plasma (ICP) spectrometry; yet, it is seldom used for forensic analysis. In this thesis, four different forensic applications will be explored using ICP spectrometry involving four different types of sample: human head hair, automotive paint, solder and gunshot residue.
Human hair and automotive paints were analyzed using electrothermal vaporization (ETV) coupled to ICP optical emission spectrometry (OES). This combination is advantageous for the analysis of forensic materials, as ETV enables the direct analysis of milligrams of solid samples, which eliminates sample contamination that could happen during dissolution. Moreover, as transport efficiency into the ICP is nearly 100%, a higher sensitivity results than with solution nebulization (SN). Qualitative analysis by ETV-ICP-OES in combination with multivariate statistical techniques, such as principal component analysis and linear discriminant analysis, enabled the discrimination of gender and general ethnicity from head hair as well as vehicle manufacturer, year of production and colour from an automotive paint chip.
Quantitative analysis by SN into ICP mass spectrometry (MS) following acid digestion constitutes an even more sensitive approach than ETV-ICP-OES. The concentrations of trace impurities were measured by SN-ICP-MS in lead-tin solder, commonly used in the making of improvised explosive devices, to help to narrow down the list of suspects if pieces of solder salvaged at the crime scene are matched to unused pieces found in a suspect’s home. Quantitative analysis by SN-ICP-MS is also useful to assess the health and safety of forensic personnel as well as cross-contamination in a forensic facility. Because forensic ballistic profiling requires a firearm discharge in an environmentally controlled range, a high concentration of lead accumulates on surfaces, exposing employees to potential lead-related health risks. In addition to quantifying the lead concentrations on surfaces in different areas, SN-ICP-MS also enabled the identification of an effective lead abatement method.
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Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada
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Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
CC0 1.0 Universal
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
CC0 1.0 Universal