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 …

Systematic Comparison Of Pre-Treatment Parameters In Forensic Hair Analysis And Investigating Hair-Drug Interactions, Jennett Chenevert Aijala

FIU Electronic Theses and Dissertations

Forensic toxicological analysis for the purposes of protecting human health and supporting criminal justice activities can be achieved, in part, by means of analysis of human head hair for detection of abused substances. Hair is considered an alternative sample matrix (compared to blood and urine) because of persistent interpretive challenges caused by a lack of standardization in analytical approaches and poor understanding of the biases resulting from physicochemical interactions between major hair components (e.g., melanin) and drugs of abuse. Some of the uncertainty regarding optimal techniques for the pre-treatment of hair specimens results from the unknown nature of the …

Structural Characterization Of Biomolecules Using Tandem Non- Linear And Linear Ion Mobility, Action Spectroscopy, Mass Spectrometry And Molecular Dynamics, Jacob Edward Porter

FIU Electronic Theses and Dissertations

The following thesis comprises the use of novel gas-phase spectroscopic and spectrometric techniques complemented with molecular dynamics for the structural characterization of biomolecules: from small model systems to large proteins. In particular, complementary linear and non-linear ion mobility, mass spectrometry and action spectroscopy has been applied to the separation and characterization of native and kinetic intermediate states of biomolecular ions. This suite of tools, comprising ion mobility in tandem with non-ergodic fragmentation and action spectroscopy, provided unique information on the conformational space, folding and binding dynamics of single stranded DNA, peptides, peptide-cofactor and protein systems. Theoretical modeling provided candidate structures …

Isolation And Characterization Of Potential Neurotoxic Cyanobacterial Metabolites Associated With Intoxication Of Captive Bottlenose Dolphins In The Florida Keys, Christina Lydon

FIU Electronic Theses and Dissertations

Bottlenose dolphins (Tursiops truncatus) living in captivity in the Florida Keys have recently been observed grazing macrophytic algal communities, and particularly, filamentous cyanobacteria, within their enclosures, and subsequently presenting apparent signs of intoxication. Collections of a mixed assemblage of marine filamentous cyanobacteria were morphologically related to the taxonomically complex and toxigenic polyphyletic genus, Lyngbya, sensu lato. Phylogenetic characterization, using 16S rDNA methods, identified an undescribed member of the recently accepted genus Neolyngbya (Oscillatoriales) among Neolyngbya arenicola, and an unknown Oscillatoriacean species within a poorly resolved clade clustering between the genera Limnoraphis and Capilliphycus.

A dual …

Lithological And Geochemical Responses To Abrupt Global And Regional Paleoenvironmental Changes During The Aptian In A Hemipelagic Setting Of The Eastern Iberian Peninsula: A Multi-Proxy Approach, Jander Socorro

FIU Electronic Theses and Dissertations

Intense episodes of environmental perturbations and regionally to globally distributed, oxygen-deprived marine facies characterize the Cretaceous sedimentary record. The Organyà Basin in the Spanish Pyrenees chronicles this period in expanded stratigraphic sequences that enabled high-resolution sampling and detailed analysis of disturbances poorly recorded in more lithologically condensed sections. Here, I present an integrated multi-proxy study aimed at understanding the Basin’s response to changing paleoenvironmental conditions during the early Aptian stage of the Cretaceous.

Results from the El Pui section indicate that large-scale (> 1‰), negative carbon isotope excursions (CIEs) that show no corresponding shifts in local sources of organic matter …

Advanced Oxidation Processes For The Remediation Of Problematic Organophosphorus Compounds And Perfluoroalkyl Substances, A M Abdullah

FIU Electronic Theses and Dissertations

The presence of persistent organic pollutants, including organophosphorus esters (OPEs) and perfluoroalkyl substances (PFASs) in drinking water sources, is a serious threat to the environment and human health. Advanced oxidation processes (AOPs), specifically TiO₂ photocatalysis and sonolysis, were evaluated to degrade these pollutants in water.

The UV/TiO₂ photocatalysis can effectively degrade tris (2-chloroethyl) phosphate (TCEP) to innocuous materials. The degradation follows pseudo-first-order kinetics and consistent with the Langmuir-Hinshelwood model. Intermediate products identified by ³¹P-NMR show sequential oxidation of alkyl chains, ultimately leading to phosphate. Scavenger studies indicate hydroxyl radical (•OH) is the primary species responsible for the …

Molecular Mechanism Of Dream Dimerization And Interactions With A Non-Physiological Ligand Zn2+., Maria D. Santiago Estevez

FIU Electronic Theses and Dissertations

Downstream Regulatory Element Antagonist Modulator (DREAM) belongs to the family of neuronal calcium sensor proteins and it is involved in several processes in the brain.

Zinc has been shown to bind to recoverin, with submillimolar affinity. Based on the high sequence homology between the NCS family, it is proposed that DREAM can also serve as an intracellular target for Zn²⁺. Fluorescence and CD studies confirm that zinc binds to DREAM with a of K_d = 4 µM, triggering changes in the proteins’ tertiary structure.

The calcium association to DREAM leads to the formation of a Ca^{2+ …}

Consequences Of Non-Physiological Ligands Binding To Dream On Its Secondary And Tertiary Structures And Interactions With Intracellular Partners., Samiol Azam

FIU Electronic Theses and Dissertations

Downstream regulatory antagonist modulator (DREAM) is 29 kDa neuronal calcium sensor (NCS) protein which is expressed in the hippocampus of the brain. DREAM is a multifunctional protein which is involved in a wide spectrum of biological processes, including regulation of potassium current in brain, modulation of pain, presenilin-1 processing, regulation of memory and learning. Exposure to toxic metals such as Pb2+ and Cd2+ have been associated with different types of neurodegenerative diseases. However, how these toxic metals induce neurotoxicity remains an active area of research. In this study, utilizing a combination of spectroscopic and calorimetric techniques, we demonstrated binding of …

Topological Markers For Subcellular Chemical Mapping Using Tof-Sims, Anthony Castellanos

FIU Electronic Theses and Dissertations

Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) is a powerful mass spectrometry imaging technique that is uniquely suited to the study of small and challenging biological samples. Mass spectrometry imaging permits the simultaneous detection of chemical species without a priori knowledge of a sample. In the present work, the use of endogenous chemical species, three-dimensional dual-beam depth profiling, and multi-modal mass spectrometry approaches are utilized to increase the specificity and reliability of sub-cellular chemical assignments. In addition, the use of these complimentary indicators serve as useful quality controls to ensure optimal preparation of samples for a high-vacuum environment. In the study …

Development Of Microfluidic Paper-Based Analytical Devices For The Detection Of Low Explosives, Kathryn R. Chabaud

FIU Electronic Theses and Dissertations

Incidents of terrorism have been on the rise despite increased government regulation of explosives. These regulations and the internet have made the application of improvised explosive devices (IEDs) such as fireworks and smokeless powders more prevalent. These devices contain low explosives which are easier to acquire than high explosives, which are more closely monitored. Pipe bombs typically contain smokeless powders, which are mostly comprised of energetics such as nitroglycerine (NG) and organic additives such as diphenylamine. Another type of easily obtainable material containing low explosives is pyrotechnics. Pyrotechnics are usually made up of a mixture of inorganic chemical oxidizers and …

Development Of Dna Methylation Markers To Infer Age, Smoking Status And Body Fluid Types For Forensic Application, Hussain J.H. Alghanim

FIU Electronic Theses and Dissertations

In forensic investigations, biological evidences have great potential to place a suspect at the scene of a crime. However, in many cases suspect(s) usually can’t be identified with any local or national databases. In such challenging cases, police need a tool that can provide investigative leads. Thus, different genetic biomarkers including DNA methylation markers have been developed for different phenotypic traits to serve as source of intelligence information to investigators in cases of unknown DNA profiles. In this project, novel sets of DNA methylation markers were developed for the forensic estimation of human age, determining the smoking status and body …

Functionalized Aptamers For Detection Of Small-Molecule Targets, Haixiang Yu

FIU Electronic Theses and Dissertations

Aptamers have recently gained considerable attention for small-molecule detection in diverse applications such as drug identification, medical diagnostics, and environmental monitoring. However, the performance of aptamer-based sensors has been greatly limited by the low target affinity and responsiveness of small-molecule binding aptamers. This dissertation describes several novel aptamer engineering and isolation strategies to remedy this problem. Specifically, we first develop a generally applicable strategy to engineer split aptamers containing two binding domains termed cooperative-binding split aptamers (CBSAs). CBSAs exhibit higher target binding affinity and are far more responsive in terms of target-induced split aptamer assembly compared to single-domain parent split …

Development Of Improved Extraction/Purification Methods And Comprehensive Screening/Confirmation By Lc-Qqq-Ms Analysis For Novel Psychoactive Substances, Ashley N. Kimble

FIU Electronic Theses and Dissertations

The presence of novel psychoactive substances (NPS) in forensic casework poses major difficulties for detection, since there are many structural variations of NPS circulating in the street market. There are currently no comprehensive screening/confirmatory/quantitation methods available that encompass the majority of NPS encountered in forensic toxicology. A major issue faced with developing such a method is that full validation is extremely time consuming. The use of a liquid chromatography triple quadrupole tandem mass spectrometry (LC-QqQ-MS/MS) method makes the detection of a large number of NPS possible because of high selectivity and sensitivity.

This research included four main tasks: 1) development …

Comprehensive Analysis Of Synthetic Cannabinoids And Metabolites In Oral Fluid By Liquid Chromatography Triple Quadrupole Mass Spectrometry, Carmen T. Mulet

FIU Electronic Theses and Dissertations

According to NIDA, synthetic cannabinoids (SC) include man-made, mind-altering chemicals. Their typically rapid metabolism and instability in biological matrices requires fast analytical methods for detection and confirmation; therefore, the use of oral fluid (OF) matrix is advantageous because collection is fast and non-invasive. The use of liquid chromatography triple quadrupole mass spectrometry (LC-QqQ-MS) and online solid phase extraction (SPE) for sample pretreatment minimizes bias and facilitates low level detection.

This study demonstrates the first use of online SPE for sample pretreatment in the comprehensive analysis of 100 SC and metabolites in OF by LC-QqQ-MS. The method was validated according the …

Towards Trigonal Prismatic Hexanuclear Copper Complexes For Catalytic Water Oxidation, David I. Kreiger

FIU Electronic Theses and Dissertations

Our planet is running out of energy resources and traditional renewables are not easily transported nor will be sufficient to cover the void left by fossil fuels. Therefore, a new energy storage system needs to be adopted. The medium with highest energy density that is readily available is hydrogen from water. However, to access hydrogen, water needs to be oxidized and water oxidation catalysts (WOCs) will be required for widespread adoption. In pursuit of WOCs, several hexauclear copper complexes were synthesized and characterized, including the isolation and characterization of a mixed-valent Cu₆ (formally, Cu^II₅Cu^III) …

Phenolate Derivatives Of Octanuclear Iron-Oxo-Pyrazolato Complexes; Enantiomeric Resolution Of T-Symmetry Species, Konstantinos Lazarou

FIU Electronic Theses and Dissertations

Octanuclear ferric complexes involving achiral phenolates of the general formula [Fe₈(μ-O)₄(μ-pz)₁₂(R-C₆H₄O)₄], (R = 4-NO₂, 4-CN, 4-F, 4-Cl, 4-I, 4-CH₃O, and 3-NO₃), where synthesized and characterized by single crystal X-ray crystallography, elemental analysis, ¹H-NMR, UV-Vis, IR, ⁵⁷Fe Mössbauer spectroscopy and electrochemical methods (cyclic and differential pulse voltammetry). Results indicate that the nature of the phenolate substituents allows the fine tuning of the spectroscopic data of the compounds.

Subsequently, this project focused on the resolution of the racemic …

Tuning The Coordination Properties Of Pyrazoles Towards Specific Applications Via Judicial Choice Of Peripheral Substitution, Shambhu Kandel

FIU Electronic Theses and Dissertations

The tunability of pyrazoles make them probably the most versatile ligands, and this is one of the right reasons to its use. Pyrazolyl ligands have intrinsic antibacterial property. Synthesis of pyrazolyl complexes with silver can be of great interest in biological applications. The urgent need to find alternative of currently used antibiotics has been recognized as a major challenge of the 21^st century. Many ideas have been proposed, but re-emergence silver could be the most promising alternative to overcome the limitations of these antibiotics. In spite of the popularity of Sonogashira coupling reactions, there is still a room to …

Interrogation Of Ion-Neutral Complexes By Trapped Ion Mobility-Mass Spectrometry And Theoretical Calculations, Alan A. Mckenzie Coe

FIU Electronic Theses and Dissertations

In the present study, the fundamentals of molecular ion trapping and the application of trapped ion mobility spectrometry coupled to mass spectrometry (TIMS-MS) to the separation and identification of molecular components in complex mixtures are shown. In particular, ion-neutral complexes lifetimes, relative stability, binding energies and candidate structures are described for common explosives during TIMS-MS, as well as the effect of the micro-environment, during complex sample analysis. A novel TIMS-MS workflow was developed for the detection of both inorganic residues (IGSR; inorganic gunshot residues) and organic residues (OGSR) of firearm discharge residue from skin swabs, capable of high specificity and …

Aptamer-Based Assay For Detection Of Ochratoxin A, Amanda Nicole Bartley

FIU Electronic Theses and Dissertations

Ochratoxin A (OTA) is a potent mycotoxin found in a wide range of agricultural products that has been linked to mitochondrial damage and renal disease. The standard methods for OTA analysis currently rely on the use of high-performance liquid chromatography (HPLC) coupled to fluorescence detection or mass spectrometry. Toward a highthroughput analysis of OTA, a single-stranded DNA aptamer, modified with a fluorophore, coupled to a complementary sequence, modified with a FRET-based quencher that dissociates in the presence of the target toxin, is proposed. In order to integrate “target trapping,” aptamer immobilization methods were explored to mediate interference issues. Assays were …

Elemental Analysis Of Adhesive Tapes By Laser-Based Methods, Claudia Martinez Lopez

FIU Electronic Theses and Dissertations

Adhesive tapes are a common type of evidence involved in violent crimes and national security threats. This research evaluated the utility of LA-ICP-MS and LIBS for the characterization of the trace elemental signature in adhesive tapes for forensic comparisons. LA-ICP-MS and LIBS methods were developed, for the first time, for the qualitative and quantitative analysis of adhesive tapes.

The backings of 90 black electrical tapes, previously characterized by conventional techniques (physical examination, IR, Py-GC-MS, and SEM-EDS), were analyzed by LA-ICP-MS to evaluate the ability of the technique to discriminate samples originating from different sources and to associate pieces of tapes …

Unrefined Humic Substances As A Potential Low-Cost Remediation Method For Groundwater Contaminated With Uranium In Acidic Conditions, Hansell Gonzalez Raymat

FIU Electronic Theses and Dissertations

Anthropogenic activities such as uranium mining and milling, nuclear weapons production, and nuclear reprocessing have left a legacy of groundwater and soil contaminated with uranium that needs to be addressed. Therefore, developing new remediation technologies to sequester uranium in situ is crucial. The objective of the study was to determine if low-cost commercially available unrefined humic substances, such as Huma-K, can be used to facilitate uranium sorption to minerals in soil and sediment. Sediments from the saturated zone beneath the F-Area seepage basins at the Savannah River Site (SRS) in South Carolina were used for the present study. The SRS …

Fundamental Mechanistic Studies On The Ultrasonic Treatment Of Problematic Water Pollutants And Toxins, Danni Cui

FIU Electronic Theses and Dissertations

Problematic organic pollutants in industrial and drinking water sources are a leading cause of water scarcity. Among the advanced oxidation processes, sonolytic degradation has received considerable attention because it combines oxidation processes initiated by reactive oxidant species and a pyrolysis processes associated with the high temperatures produced during cavitation.

The degradation of the semi-volatile compound, MCHM, was rapid and followed pseudo-first order kinetics. The Freundlich kinetic model for heterogeneous systems was successfully applied to describe the non-uniform distribution of MCHM at the gas-liquid interface during ultrasonic treatment. Two primary products were confirmed by GC-MS. Computational studies were also applied to …

Mapping Of The Chromium And Iron Pyrazolate Landscape, Jessica Maria Lopez

FIU Electronic Theses and Dissertations

The main objective of this project is to synthesize the first family of polynuclear chromium pyrazolate complexes. Complexity in analysis of the experimental magnetic data of multinuclear complexes arises from their (2S +1)^N microstates, where S is the spin of each metal center and N is the number of metal centers. For example, high-spin (HS)-Fe^III₃ has 216 microstates and HS-Fe^III₈ ≈ 1.7x10⁶ microstates (S= 5/2). However, complexes with chromium(III) S = 3/2 will have a noticeable reduction of microstates. Mononuclear complexes with formula [mer-CrCl₃(pzH*)₃] (pz*H = pyrazole, 3-Me-pzH, …

An Investigation Into The Adduct Forming Potential Of Drugs Of Abuse With Peptides And Proteins, Richard Allen Gilliland

FIU Electronic Theses and Dissertations

Hemoglobin and serum albumin, two prevalent proteins in human blood, contain unbound cysteine thiol moieties, creating a nucleophilic site with the potential for covalent modification by reactive chemical species. These covalent modifications, called “adducts”, are stable entities that accumulate during acute and chronic exposure and remain covalently bound for the life-span of the protein. Despite their current use as exposure markers for a variety of compounds, the use of adducts in assessing exposure to drugs of abuse has not yet been explored. The goal of this work was to examine the in vitro adduct forming capability of selected drugs of …

Forensic Toxicological Screening And Confirmation Of 800+ Novel Psychoactive Substances By Lc-Qtof-Ms And 2d-Lc Analysis, Melanie N. Eckberg

FIU Electronic Theses and Dissertations

Novel psychoactive substances (NPS) represent a great challenge to toxicologists due to the ability of illicit drug manufacturers to alter NPS chemical structures quickly and with ease to circumvent legislation regulating their use. Each time a new structure is introduced, there is a possibility that it has not been previously recorded in law enforcement or scientific databases. Many toxicology laboratories use targeted analytical methods that rely on libraries of known compounds to identify drugs in samples. However, these libraries do not include large numbers of NPS which could result in non-identification or detection.

High-resolution mass spectrometry (HRMS) has been suggested …

Characterization Of The Uranium-Bearing Phases Produced By Novel Remediation Technologies For Sequestration Of Mobile Radiological Contaminants In The Hanford 200 Area Vadose Zone, Robert Michael Lapierre

FIU Electronic Theses and Dissertations

Of the many toxic chemicals released into the Hanford vadose zone over the decades of nuclear weapons production, uranium has emerged as a contaminant of significant interest. The ammonia gas injection remediation method has been identified as a promising approach towards mitigating the risks to the ecosystem by limiting the mobility of the radionuclide in the vadose zone. The remediation method was replicated using synthetic porewater solutions with a range of constituent concentrations equal to that of the Hanford 200 Area vadose zone. The uranium-bearing products of the remediation method were characterized using kinetic phosphorescence analysis for aqueous uranium, scanning …

Interaction Of High Molecular Weight Compounds With A, Β-Unsaturated Carbonyl Moiety With Mammalian And Drosophila Melanogaster Thioredoxin Reductase, Anupama Tuladhar

FIU Electronic Theses and Dissertations

The thioredoxin system is the major cellular reductant system present in the cell, whose role is to maintain cellular redox homeostasis. It does this in part, by regulating the activity of many other enzymes including ribonucleotide reductase, which is essential for DNA synthesis. It also acts as an antioxidant, reducing destructive reactive oxygen species. The thioredoxin system is comprised of thioredoxin (Trx) which reduces target protein disulfide bridges by thiol-disulfide exchange and thioredoxin reductase (TrxR) which reduces Trx back to its active state. Thioredoxin reductase is a common target for many cancer drugs including cisplatin and auranofin. Recently we have …

Aptamer Sensors For Drugs Of Abuse And Medical Biomarkers: Design, Engineering And Application In Complex Samples, Daniel Roncancio

FIU Electronic Theses and Dissertations

Aptamers are short oligonucleotide sequences (DNA or RNA) capable of high affinity and specific binding to a molecule or a family of molecules. Aptamers are lower in cost and exhibit higher reproducibility when compared to antibodies and thus are well-suited for recognition and detection of small molecular targets such as drugs of abuse and small medical biomarkers. While aptamers have been extensively utilized for development of small molecule sensors, several limitations prevent measurements of complex or real-world samples. This dissertation describes methods, technologies, and assays that were developed with the goal of producing and/or improving aptamer-based sensors for target detection …

New Polynuclear Copper-Pyrazolate Complexes: Towards The Synthesis Of Photo- And Redox-Active Metal Organic Frameworks, Kaige Shi

FIU Electronic Theses and Dissertations

The main objectives of this project are the synthesis and redox- or photo-active modification and CO₂ adsorption studies of metal-organic frameworks (MOFs) based on Cu₃-pyrazolate secondary building units (SBUs). Trinuclear copper(II) complexes of the formula [Cu₃(µ₃-O)(µ-4-R-pz)₃X₃]^z have been studied extensively due to their redox, magnetic and catalytic properties. In earlier work, we have shown that trinuclear copper(II) complexes of the formula [Cu₃(µ₃-O)(µ-4-R-pz)₃X₃]^z pz = pyrazolato anion; R = H, CH(O), Cl, Br and NO₂; X = Cl, …

Predicting The Geographic Origin Of Heroin By Multivariate Analysis Of Elemental Composition And Strontium Isotope Ratios, Joshua S. Debord

FIU Electronic Theses and Dissertations

The goal of this research was to aid in the fight against the heroin and opioid epidemic by developing new methodology for heroin provenance determination and forensic sample comparison. Over 400 illicit heroin powder samples were analyzed using quadrupole and high-resolution inductively-coupled plasma mass spectrometry (Q-ICP-MS and HR-ICP-MS) in order to measure and identify elemental contaminants useful for associating heroin samples of common origin and differentiating heroin of different geographic origins. Additionally, 198 heroin samples were analyzed by multi-collector ICP-MS (MC-ICP-MS) to measure radiogenic strontium isotope ratios (⁸⁷Sr/⁸⁶Sr) with high-precision for heroin provenance determination, for the …