Analytical Chemistry Commons^™

Use Of Laser Induced Breakdown Spectroscopy For The Detection And Analysis Of Chemical Taggants, Cole Andrew Pajunen

FIU Electronic Theses and Dissertations

Chemical taggants impart a unique imprint on an object so that, if stolen, the ownership or original source of the object can be unambiguously identified. A commercially available tagging system from SmartWater® Technology Ltd. utilizes a polymer-based solution that solidifies upon application and contains a unique combination of up to 27 rare-earth elements as the chemical identification system. Currently, Laser ablation inductively coupled mass spectrometry (LA-ICP-MS) is used as the primary means to determine the presence/absence of these elements. This current study investigates the use of a commercial laser induced breakdown spectroscopy (LIBS) system as an alternative detection method due …

Elemental Characterization Of Printing Inks And Strengthening The Evaluation Of Forensic Glass Evidence, Ruthmara Corzo

FIU Electronic Theses and Dissertations

Improvements in printing technology have exacerbated the problem of document counterfeiting, prompting the need for analytical techniques that better characterize inks for forensic analysis. In this study, 319 printing inks (toner, inkjet, offset, and intaglio) were analyzed directly on the paper substrate using Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS). As anticipated, the high sensitivity of LA-ICP-MS resulted in excellent discrimination (> 99%) between ink samples originating from different sources. Moreover, LA-ICP-MS provided ≥ 90% correct association for ink samples originating from the same source. SEM-EDS resulted in good discrimination for toner and intaglio …

Determination Of The Zinc Concentration In Human Fingernails By Laser-Induced Breakdown Spectroscopy, Steven J. Rehse, Vlora A. Riberdy, Christopher J. Frederickson

Physics Publications

The absolute concentration of zinc in human fingernail clippings tested ex vivo was determined by 1064 nm laser-induced breakdown spectroscopy and confirmed by speciated isotope dilution mass spectrometry. A nail testing protocol that sampled across the nail (perpendicular to the direction of growth) was developed and validated by scanning electron microscopy energy dispersive x-ray spectroscopy. Using this protocol, a partial least squares regression model predicted the zinc concentration in five subjects’ fingernails to within 7 ppm on average. The variation of the zinc concentration with depth into the nail as determined by laser-induced breakdown spectroscopy was studied and found to …

Fast Detection And Chemical Characterization Of Gunshot Residues By Cmv-Gc-Ms And Libs, Anamary Tarifa

FIU Electronic Theses and Dissertations

Gunshot residue (GSR) is the term used to describe the particles originating from different parts of the firearm and ammunition during the discharge. A fast and practical field tool to detect the presence of GSR can assist law enforcement in the accurate identification of subjects.

A novel field sampling device is presented for the first time for the fast detection and quantitation of volatile organic compounds (VOCs). The capillary microextraction of volatiles (CMV) is a headspace sampling technique that provides fast results (< 2 min. sampling time) and is reported as a versatile and high-efficiency sampling tool. The CMV device can be coupled to a Gas Chromatography-Mass Spectrometry (GC-MS) instrument by installation of a thermal separation probe in the injection port of the GC.

An analytical method using the CMV device was developed for the detection of 17 compounds commonly found …

Elemental Analysis Of Printing Inks Using Tandem Laser- Induced Breakdown Spectroscopy And Laser Ablation Inductively Coupled Plasma Mass Spectrometry, Kiran Subedi

FIU Electronic Theses and Dissertations

As a consequence of the widespread use of computers coupled to high-quality printers and different types of papers, forgery, counterfeiting, change of wills, anonymous letter writing and felonious use of the documents have become serious problems. Forensic analysts are always seeking methods that can provide reliable information on whether a specimen collected at the crime scene is linked to the crime or to a source of known origin. Sensitive methods that can provide more detailed characterization of natural or man-made materials or even provide information not previously available to forensic examiners.

Recent advances in rapid solid sampling of materials using …

Analysis Of White Latex Paints Using Laser Induced Breakdown Spectroscopy For Forensic Applications, Melissa Zwilling

FIU Electronic Theses and Dissertations

The analysis of white latex paint is a problem for forensic laboratories because of difficulty in differentiation between samples. Current methods provide limited information that is not suitable for discrimination. Elemental analysis of white latex paints has resulted in 99% discriminating power when using LA-ICP-MS; however, mass spectrometers can be prohibitively expensive and require a skilled operator. A quick, inexpensive, effective method is needed for the differentiation of white latex paints.

In this study, LIBS is used to analyze 24 white latex paint samples. LIBS is fast, easy to operate, and has a low cost. Results show that 98.1% of …

Elemental Analysis And Forensic Comparison Of Soils By Laser-Induced Breakdown Spectroscopy (Libs) And Laser Ablation Inductively Coupled Plasma Mass Spectrometry (La-Icp-Ms), Sarah C. Jantzi

FIU Electronic Theses and Dissertations

The elemental analysis of soil is useful in forensic and environmental sciences. Methods were developed and optimized for two laser-based multi-element analysis techniques: laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and laser-induced breakdown spectroscopy (LIBS). This work represents the first use of a 266 nm laser for forensic soil analysis by LIBS.

Sample preparation methods were developed and optimized for a variety of sample types, including pellets for large bulk soil specimens (470 mg) and sediment-laden filters (47 mg), and tape-mounting for small transfer evidence specimens (10 mg). Analytical performance for sediment filter pellets and tape-mounted soils was similar …