Physical Sciences and Mathematics Commons^™

Mass Spectral And Chemometric Analysis For The Detection And Identification Of Forensically Relevant Materials, Meghan Grace Appley

Legacy Theses & Dissertations (2009 - 2024)

Forensic science is the application of science to the law which in and of itself covers a substantial number of disciplines. Many of these involve the detection and identification of materials using analytical techniques. Traditional analysis methods include microscopy, spectroscopy and mass spectrometry. The materials encountered by forensic practitioners are ever evolving, resulting in the need to develop new methods to complement conventional techniques to enhance the evidentiary value of the samples. The research presented here shows that novel methods including direct analysis in real time–high-resolution mass spectrometry (DART-HRMS), thermal desorption coupled with gas chromatography-mass spectrometry (TD-GC-MS), solid-phase microextraction (SPME) …

Studies Of Flerovium And Element 115 Homologs With Macrocyclic Extractants, John Dustin Despotopulos

UNLV Theses, Dissertations, Professional Papers, and Capstones

Study of the chemistry of the heaviest elements, Z ≥ 104, poses a unique challenge due to their low production cross-sections and short half-lives. Chemistry also must be studied on the one-atom-at-a-time scale, requiring automated, fast, and very efficient chemical schemes. Recent studies of the chemical behavior of copernicium (Cn, element 112) and flerovium (Fl, element 114) together with the discovery of isotopes of these elements with half-lives suitable for chemical studies have spurred a renewed interest in the development of rapid systems designed to study the chemical properties of elements with Z ≥ 114. This dissertation explores both extraction …

Characterization And Optimization Of Extraction Chromatography Resins For Rapid Separations For Safeguard And Nuclear Forensics Purposes, Audrey Roman

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this work, extraction chromatography resins, DGA and UTEVA, were characterized under various conditions in order to identify novel rapid separations for safeguards and nuclear forensic purposes. For safeguards purposes, mixed matrices containing some of the largest components found in used fuel and either Am, Pu, or U were characterized on DGA and UTEVA resins in order to determine any effects from the addition of these constituents. Results indicated that 5 M HNO₃ would be an optimal loading condition due to the consistent actinide adsorption in the presence of the additional used fuel components. Investigations of varying the anion …

The Relative Recoverability Of Dna And Rna Profiles From Forensically Relevant Body Fluid Stains, Charly Parker

Electronic Theses and Dissertations

Biological material (fluids or tissues) whether from the victim or suspect is often collected as forensic evidence, and methods to obtain and analyze the DNA found in that material have been well established. The type of body fluid (i.e. blood, saliva, semen, vaginal secretions, and menstrual blood) from which the DNA originated is also of interest, and messenger RNA typing provides a specific and sensitive means of body fluid identification. In order for mRNA profiling to be utilized in routine forensic casework, RNA of sufficient quantity and quality must be obtained from biological fluid stains and the methods used for …

Preparation And Characterization Of Extraction Chromatography Resins Using N-Donor Extractants For Trivalent Actinide And Lanthanide Separations, Christopher L. Klug

UNLV Theses, Dissertations, Professional Papers, and Capstones

Actinide and lanthanide elements exist in the geosphere and biosphere due to both natural abundances and anthropogenic activities. The investigation of the presence and transport of actinides through the environment is of great scientific interest. In order to prepare environmental samples for precise measurements, the individual actinides must be separated from the chemically similar lanthanides, and from neighboring actinides. Existing extraction chromatography resins are either poorly suited for this separation, have bleeding problems, are not reusable, or fail the CHON principle. In an effort to resolve these issues, malonamides and N-donor extractants from the BTP and BTBP classes of solvent …

Ecological Method Development For Detecting N-Nitrosodimethylamine In Water Using Hplc-Pdad, Jolisa Mcday

Master's Theses and Doctoral Dissertations

Using ethanol, a sustainable reversed-phase high-performance liquid chromatographic method with photo-diode array detection (HPLC-PDAD) was investigated to detect sub-parts per billion concentrations of N-nitrosodimethylamine (NDMA) in drinking water and environmental water samples. This presents a practical and “green” option to analytical methods that require laborious derivatization, expensive detectors and unecological solvents.

Mobile phase characteristics, instrument operating parameters, and sample preparation were investigated. Selectivity for NDMA was evaluated using three different C18 columns. Optimal peak resolution and detection were achieved at 231 nm. The limit of detection and quantitation for NDMA was 0.29 μg/mL and 0.96 μg/mL, respectively, with an ethanol …

Novel Improvements On The Analytical Chemistry Of Polycyclic Aromatic Hydrocarbons And Their Metabolites, Wang Huiyong

Electronic Theses and Dissertations

Polycyclic aromatic hydrocarbons (PAH) are important environmental pollutants originating from a wide variety of natural and anthropogenic sources. Because many of them are highly suspect as etiological agents in human cancer, chemical analysis of PAH is of great environmental and toxicological importance. Current methodology for PAH follows the classical pattern of sample preparation and chromatographic analysis. Sample preparation preconcentrates PAH, simplifies matrix composition, and facilitates analytical resolution in the chromatographic column. Among the several approaches that exist to pre-concentrate PAH from water samples, the Environmental Protection Agency (EPA) recommends the use of solid-phase extraction (SPE). High-performance liquid chromatography (HPLC) and …

Development Of A Headspace Solid-Phase Microextraction (Hs-Spme) Procedure For The Determination Of Short-Chain Fatty Acids (Scfas) In Activated Sludge By Gc-Fid, Shiyan Cheng

Master's Theses and Doctoral Dissertations

The process of wastewater treatment includes the removal of inorganic solids such as sand and gravel as well as organic materials, phosphorus, and nitrogen. Activated sludge, containing a variety of living organisms, is added into the wastewater treatment system. Short-chain fatty acids (SCFAs), an energy source of the bioorganisms, are produced during activated sludge digestion, and play a significant role in phosphorus and nitrogen removal as well as the removal of organic materials during the process of wastewater treatment. Extensive research has been carried out recently in search of optimized conditions to increase the level of fatty acids in the …