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- Title
- NEW DEVELOPMENTS ON HIGH-RESOLUTION LUMINESCENCE SPECTROSCOPY AND THEIR APPLICATION TO THE DIRECT ANALYSIS OF ORGANIC POLLUTANTS IN ENVIRONMENTAL SAMPLES.
- Creator
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yu, shenjiang, Campiglia, Andres, University of Central Florida
- Abstract / Description
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Polycyclic aromatic compounds (PACs), which comprise a complex class of condensed multi-ring benzenoid compounds, are important environmental pollutants originating from a wide variety of natural and anthropogenic sources. PACs are generally formed during incomplete combustion of pyrolisis of organic matter containing carbon and hydrogen. Because combustion of organic materials is involved in countless natural processes or human activities, PACs are omnipresent and abundant pollutants in air,...
Show morePolycyclic aromatic compounds (PACs), which comprise a complex class of condensed multi-ring benzenoid compounds, are important environmental pollutants originating from a wide variety of natural and anthropogenic sources. PACs are generally formed during incomplete combustion of pyrolisis of organic matter containing carbon and hydrogen. Because combustion of organic materials is involved in countless natural processes or human activities, PACs are omnipresent and abundant pollutants in air, soil, and water. Chemical analysis of PACs is of great environmental and toxicological importance. Many of them are highly suspect as etiological agents in human cancer. Because PACs carcinogenic properties strongly depend on molecular structure and differ significantly from isomer to isomer, it is of paramount importance to determine the most toxic isomers even if they are present at much lower concentrations than their less toxic isomers. Gas chromatography (GC), high-resolution GC, and high-performance liquid chromatography (HPLC) are the basis for standard PACs identification and determination. Many cases exist where GC, HPLC, and even HR-GC have not been capable to provide unambiguous isomer identification. The lack of reliable analytical data has lead to serious errors in environmental and toxicological studies. This dissertation deals with the development of novel instrumentation and analytical methods for the analysis of PACs in environmental samples. The developed methodology is based on two well-known high-resolution luminescence techniques, namely Shpol'skii Spectroscopy (SS) and Fluorescence Line Narrowing Spectroscopy (FLNS). Although these two techniques have long been recognized for their capability in providing direct determination of target PACs in complex environmental samples, several reasons have hampered their widespread use for the problem at hand. These include inconvenient sample freezing procedures; questions about signal reproducibility; lengthy spectral acquisition, which might cause severe sample degradation due to prolonged excitation; broadband fluorescence background that degrades quality of spectra, precision of measurements and detection limits; solvent constrains imposed by the need of optically transparent media; and, most importantly, the lack of selectivity and sensitivity for unambiguous determination of closely related PACs metabolites. This dissertation presents significant advances on all fronts. The analytical methodology is then extended to the analysis of fluoroquinolones (FQs) in aqueous samples. FQs are one of the most powerful classes of antibiotics currently used for the treatment of urinary tract infections. Their widespread use in both human and animal medicine has prompted their appearance in aquatic systems. The search for a universal method capable to face this new environmental challenge has been centered on HPLC. Depending on the FQ and its concentration level, successful determination has been accomplished with mass spectrometry, room-temperature fluorescence (RTF) or UV absorption spectrometry. Unfortunately, no single detection mode has shown the ability to detect all FQ at the concentration ratios found in environmental waters. We provide a feasible alternative based on FLNS. On the instrumentation side, we present a single instrument with the capability to collect multidimensional data formats in both the fluorescence and the phosphorescence time domains. We demonstrate the ability to perform luminescence measurements in highly scattering media by comparing the precision of measurements in optically transparent solvents (Shpol'skii solvents) to those obtained in "snow-like" matrixes and solid samples. For decades, conventional low-temperature methodology has been restricted to optically transparent media. This restriction has limited its application to organic solvents that freeze into a glass. In this dissertation, we remove this limitation with the use of cryogenic fiber-optic probes. Our final efforts deal with low-temperature absorption measurements. Recording absorption spectra via transmittance through frozen matrixes is a challenging task. The main reason is the difficulty to overcome the strong scattering light reaching the detector. This is particularly true when thick samples are necessary for recording absorption spectra of weak oscillators. In the case of strongly fluorescent compounds, additional errors in absorbance measurements arise from the emission reaching the detector, which might have comparable intensity to that of the transmitted light. We present a fundamentally different approach to low-temperature absorption measurements as the sought-for-information is the intensity of laser excitation returning from the frozen sample to the intensified-charge coupled device (ICCD). Laser excitation is collected with the aid of a cryogenic fiber optic probe. The feasibility of our approach is demonstrated with single-site and multiple-site Shpol'skii systems. 4.2K absorption spectra show excellent agreement to their literature counterparts recorded via transmittance with closed cycle cryogenators. Fluorescence quantum yields measured at room-temperature compare well to experimental data acquired in our lab via classical methodology. Similar agreement is observed between 77K fluorescence quantum yields and previously reported data acquired with classical methodology. We then extend our approach to generate original data on fluorescence quantum yields at 4.2K.
Show less - Date Issued
- 2006
- Identifier
- CFE0001456, ucf:47039
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001456
- Title
- ANALYTICAL POTENTIAL OF POLYMERIZED LIPOSOMES BOUND TO LANTHANIDE IONS FOR QUALITATIVE AND QUANTITATIVE ANALYSIS OF PROTEINS.
- Creator
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Santos, Marina, Campiglia, Andres, University of Central Florida
- Abstract / Description
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One of the intriguing features of biological systems is the prevalence of highly selective and often very strong interactions among different cellular components. Such interactions play a variety of organizational, mechanical, and physiological roles at the cellular and organism levels. Antigen-antibody complexes are representative examples of highly selective and potent interactions involving proteins. The marked specificity of protein-antibody complexes have led to a wide range of...
Show moreOne of the intriguing features of biological systems is the prevalence of highly selective and often very strong interactions among different cellular components. Such interactions play a variety of organizational, mechanical, and physiological roles at the cellular and organism levels. Antigen-antibody complexes are representative examples of highly selective and potent interactions involving proteins. The marked specificity of protein-antibody complexes have led to a wide range of applications in cellular and molecular biology related research. They have become an integral research tool in the present genomic and proteomic era. Unfortunately, the production of selective tools based on antigen-antibody interactions requires cumbersome protocols. The long term goal of this project explores the possibility of manipulating liposomes to serve as the chemical receptors ("artificial antibodies") against selected proteins. Cellular lipids (e.g., lipid rafts) are known to facilitate highly selective binding of proteins on cell membranes. The binding of proteins to cell membranes can be envisaged to be modulated via interactions between polar (charged) and non-polar head groups of lipids and the complementary amino acid residues of proteins. Their interaction is facilitated by a combination of van der Waals, electrostatic, hydrogen bonding and hydrophobic forces. A further interesting aspect of the above interaction is the "fluidity" of the membrane resident lipids, which can migrate from other regions to further enhance the complementary interactions of proteins on the initially "docked" membrane surface. With these features in mind, the end goal of this project is expected to deliver lipid-based chemical receptors "synthetically" designed against proteins to function as "artificial antibodies". Protein sensing will be accomplished with lipid receptors assembled in templated polymerized liposomes. The research presented here specifically focus on the analytical aspects of protein sensing via polymerized liposome vesicles. Lanthanide ions (Eu3+ and Tb3+) are incorporated into polymerized liposome with the expectation to "report" quantitative and qualitative information on the interacting protein. Our proposition is to extract quantitative and qualitative information from the luminescence intensity and the luminescence lifetime of the lanthanide ion, respectively. A thorough investigation is presented regarding the analytical potential of these two parameters for protein sensing. Two chemometic approaches - namely partial least squares (PLS-1) and artificial neural networks (ANN) - are compared towards quantitative and qualitative analysis of proteins in binary mixtures.
Show less - Date Issued
- 2007
- Identifier
- CFE0001373, ucf:46999
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001373
- Title
- ANALYTICAL EVALUATION OF THE FLUORESCENCE CHARACTERISTICS OF METABOLITES OF POLYCYCLIC AROMATIC HYDROCARBONS AT ROOM, LIQUID NITROGEN AND LIQUID HELIUM TEMPERATURES.
- Creator
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Vatsavai, Keerthika, Campiglia, Andres, University of Central Florida
- Abstract / Description
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Although environmental monitoring of polycyclic aromatic hydrocarbons (PAH) is an essential step to prevent human exposure to contaminated sites, it provides little information on the actual human uptake and subsequent risks. To this end, urine analysis of short-term biomarkers such as PAH metabolites fill an important niche. The general approach follows the sequence of urine hydrolysis, sample clean-up and pre-concentration, chromatographic separation and determination. Whereas...
Show moreAlthough environmental monitoring of polycyclic aromatic hydrocarbons (PAH) is an essential step to prevent human exposure to contaminated sites, it provides little information on the actual human uptake and subsequent risks. To this end, urine analysis of short-term biomarkers such as PAH metabolites fill an important niche. The general approach follows the sequence of urine hydrolysis, sample clean-up and pre-concentration, chromatographic separation and determination. Whereas chromatographic methods are based on well established laboratory techniques, the development of easy-to-use, cost-effective and large sample throughput techniques is becoming increasingly relevant to investigate adverse PAH effects on large human populations. This thesis compares the room-temperature, 77K and 4.2K fluorescence properties of 1-naphthol, 2-naphthol, 1-hydroxypyrene, 2-hydroxyfluorene, 3-hydroxybenzopyrene and 9-hydroxyphenanthrene. These metabolites are used as model biomarkers to investigate the analytical potential of a simple method of analysis based on Solid-Phase Extraction and Room-Temperature Fluorimetry. Metabolites are directly determined in the eluting solvent (methanol) without the need of previous separation via multidimensional formats. Metabolite recoveries varied between 87 ± 1.51% (9-hydroxyphenanthrene) and 99 ± 1.05% (3-hydroxybenzopyrene). For 10mL of urine samples, limits of detection varied between 0.01ng.mL-1 (3-hydroxybenzopyrene) and 0.6ng.mL-1 (2-hydroxynaphthalene). These figures of merit demonstrate the potential of this approach for screening purposes
Show less - Date Issued
- 2007
- Identifier
- CFE0001946, ucf:47461
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001946
- Title
- ROOM TEMPERATURE FLUORESCENCE SPECTROSCOPY AS A TOOL FOR THE FORENSIC TRACE ANALYSIS OF TEXTILE FIBERS.
- Creator
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Rex, Matthew, Campiglia, Andres, University of Central Florida
- Abstract / Description
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ABSTRACT Trace textile fiber evidence is found at numerous crime scenes and plays an important role in linking a suspect to the respective scene. Several methods currently exist for the analysis of trace fiber evidence. Microscopy provides information regarding the fibers material, color and weave. For more detailed chemical analysis chromatographic methods are employed and for discrimination between dyes, liquid chromatography coupled with mass spectrometry (LC-MS) is currently the method...
Show moreABSTRACT Trace textile fiber evidence is found at numerous crime scenes and plays an important role in linking a suspect to the respective scene. Several methods currently exist for the analysis of trace fiber evidence. Microscopy provides information regarding the fibers material, color and weave. For more detailed chemical analysis chromatographic methods are employed and for discrimination between dyes, liquid chromatography coupled with mass spectrometry (LC-MS) is currently the method providing the most discrimination. These methods have primarily focused on the dyes used to color the fibers and have not investigated other components that can potentially discriminate among fibers. This dissertation deals with investigations into the fluorescence of the fiber dyes, (contaminants?) and the fibers themselves, as well as methodology for discriminating between fibers using fluorescence. Initial systematic analysis was conducted on dye standards and extracts taken from fibers colored with the respective dyes of interest. Absorbance, excitation and fluorescence spectra were compared between standards and extracts to determine the optimal area of the fiber to investigate: dyes, fluorescent impurities or the whole fiber. High performance liquid chromatography investigations were performed to give detailed information on the number of dye and fluorescent components present in extracts. Our investigations then focused on the best room-temperature fluorescence (RTF) data format for analysis and discrimination of fiber samples. An excitation emission matrix (EEM) was found to give the greatest amount of spectral information and provide the highest level of discrimination. Successful discrimination between non similar and similar fibers was achieved with the aid of Chemometric analysis. The level of discrimination obtained via RTF-EEM spectroscopy was sufficient to differentiate among fibers obtained from two separate cloths of the same material and colored with the same dye reagent. Final studies deal with examining exposure of the fiber to various environmental contaminants. Clothing fibers are typically exposed to myriad numbers of contaminants, from food stains to cigarette smoke. The challenge then becomes detecting fluorescence signals from trace amounts of these environmental contaminants. We demonstrate the detection and classification of polycyclic aromatic hyrdrocarbons (PAH) present on fibers after exposure to cigarette smoke. This dissertation also investigates the change in fluorescence emission after laundering fibers numerous times. The main drawback of chemical analysis of fibers is the destructive nature of the methods. To extract a dye or contaminant from a fiber essentially destroys the evidence. This leaves the investigator without their original sample in the courtroom. This also provides a finite amount of sample for testing and analysis. This is true of chromatographic methods and for the method detailed in this dissertation which makes use of extracts taken from fiber samples. Lastly, we propose an instrumental setup coupling a microscope to a spectrofluorimeter for the purpose of taking EEM directly from a fiber sample. This setup makes use of the superior optics of the microscope for focusing excitation light onto the fiber sample. Initial studies have been performed on extracts from a single textile fiber and EEM collected from said fiber.
Show less - Date Issued
- 2009
- Identifier
- CFE0002833, ucf:48084
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002833
- Title
- NOVEL IMPROVEMENTS ON THE ANALYTICAL CHEMISTRY OF POLYCYCLIC AROMATIC HYDROCARBONS AND THEIR METABOLITES.
- Creator
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Wang, Huiyong, Campiglia, Andres, University of Central Florida
- Abstract / Description
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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 pre-concentrates PAH, simplifies matrix composition, and...
Show morePolycyclic 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 pre-concentrates 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 gas chromatography-mass spectrometry (GC-MS) are the basis for standard PAH identification and determination. Ultraviolet (UV) absorption and room temperature fluorescence detection are both widely used in HPLC, but the specificity of these detectors is modest. Since PAH identification is solely based on retention times, unambiguous PAH identification requires complete chromatographic resolution of sample components. When HPLC is applied to "unfamiliar" samples, the EPA recommends that a supporting analytical technique such as GC-MS be applied to verify compound identification and to check peak-purity HPLC fractions. Independent of the volume of extracted water, the approximate time required to separate and determine the sixteen "priority pollutants" (EPA-PAH) via HPLC is approximately 60min. If additional GC-MS analysis is required for unambiguous PAH determination, the total analysis time will reach 2-3 hours per sample. If the concentrations of target species are found to lie outside the detector's response range, the sample must be diluted and the process repeated. These are important considerations when routine analysis of numerous samples is contemplated. Parent PAH are relatively inert and need metabolic activation to express their carcinogenicity. By virtue of the rich heterogeneous distribution of metabolic products they produce, PAH provide a full spectrum of the complexity associated with understanding the initial phase of carcinogenesis. PAH metabolites include a variety of products such as expoxides, hydroxyl aromatics, quinines, dihydrodiols, dioepoxides, tetrols and water soluble conjugates. During the past decades tremendous efforts have been made to develop bio-analytical techniques that possess the selectivity and sensitivity for the problem at hand. Depending on the complexity of the sample and the relative concentrations of the targeted metabolites, a combination of sample preparation techniques is often necessary to reach the limits of detection of the instrumental method of analysis. The numerous preparation steps open ample opportunity to metabolite loss and collection of inaccurate data. Separation of metabolites has been accomplished via HPLC, capillary electrophoresis (CE) and GC-MS. Unfortunately, the existence of chemically related metabolic products with virtually identical fragmentation patterns often challenges the specificity of these techniques. This dissertation presents significant improvements in various fronts. Its first original component - which we have named solid-phase nano-extraction (SPNE) - deals with the use of gold nanoparticles (Au NPs) as extracting material for PAH. The advantages of SPNE are demonstrated for the analysis of PAH in water samples via both HPLC and Laser-Excited Time-Resolved Shpol'skii Spectroscopy (LETRSS). The same concept is then extended to the analysis of monohydroxy-PAH in urine samples via SPE- HPLC and In-Capillary SPNE-CE. The second original component of this dissertation describes the application of Shpol'skii Spectroscopy to the analysis of polar PAH metabolites. The outstanding selectivity and sensitivity for the direct analysis of PAH at trace concentration levels has made Shpol'skii spectroscopy a leading technique in environmental analysis. Unfortunately, the requirement of a specific guest-host combination - typically a non-polar PAH dissolved in an n-alkane - has hindered its widespread application to the field of analytical chemistry. This dissertation takes the first steps in removing this limitation demonstrating its feasibility for the analysis of polar benzopyrene metabolites in alcohol matrixes.
Show less - Date Issued
- 2010
- Identifier
- CFE0003202, ucf:48579
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0003202
- Title
- Photoactivatable Organic and Inorganic Nanoparticles in Cancer Therapeutics and Biosensing.
- Creator
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Mathew, Mona, Gesquiere, Andre, Hickman, James, Ye, Jingdong, Campiglia, Andres, Schoenfeld, Winston, University of Central Florida
- Abstract / Description
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In photodynamic therapy a photosensitizer drug is administered and is irradiated with light. Upon absorption of light the photosensitizer goes into its triplet state and transfers energy or an electron to oxygen to form reactive oxygen species (ROS). These ROS react with biomolecules in cells leading to cell damage and cell death. PDT has interested many researchers because of its non-invasiveness as compared to surgery, it leaves little to no scars, it is time and cost effective, it has...
Show moreIn photodynamic therapy a photosensitizer drug is administered and is irradiated with light. Upon absorption of light the photosensitizer goes into its triplet state and transfers energy or an electron to oxygen to form reactive oxygen species (ROS). These ROS react with biomolecules in cells leading to cell damage and cell death. PDT has interested many researchers because of its non-invasiveness as compared to surgery, it leaves little to no scars, it is time and cost effective, it has potential for targeted treatment, and can be repeated as needed. Different photosensitizers such as porphyrines, chlorophylls, and dyes have been used in PDT to treat various cancers, skin diseases, aging and sun-damaged skin. These second generation sensitizers have yielded reduced skin sensitivity and improved extinction coefficients (up to ~ 105 L mol-1 cm-1). While PDT based on small molecule photosensitizers has shown great promise, several problems remain unsolved. The main issues with current sensitizers are (i) hydrophobicity leading to aggregation in aqueous media resulting in reduced efficacy and potential toxicity, (ii) dark toxicity of photosensitizers, (iii) non-selectivity towards malignant tissue resulting in prolonged cutaneous photosensitivity and damage to healthy tissue, (iv) limited light absorption efficiency, and (v) a lack of understanding of where the photosensitizer ends up in the tissue. In this dissertation research program, these issues were addressed by the development of conducting polymer nanoparticles as a next generation of photosensitizers. This choice was motivated by the fact that conducting polymers have large extinction coefficients ((>) 107 L mol-1 cm-1), are able to undergo intersystem crossing to the triplet state, and have triplet energies that are close to that of oxygen. It was therefore hypothesized that such polymers could be effective at generating ROS due to the large excitation rate that can be generated. Conducting polymer nanoparticles (CPNPs) composed of the conducting polymer poly[2-methoxy-5-(2-ethylhexyl-oxy)-p-phenylenevinylene] (MEH-PPV) were fabricated and studied in-vitro for their potential in PDT application. Although not fully selective, the nanoparticles exhibited a strong bias to the cancer cells. The formation of ROS was proven in-vitro by staining of the cells with CellROX Green Reagent, after which PDT results were quantified by MTT assays. Cell mortality was observed to scale with nanoparticle dosage and light dosage. Based on these promising results the MEH-PPV nanoparticles were developed further to allow for surface functionalization, with the aim of targeting these NPs to cancer cell lines. For this work targeting of cancers that overexpress folate receptors (FR) were considered. The functionalized nanoparticles (FNPs) were studied in OVCAR3 (ovarian cancer cell line) as FR+, MIA PaCa2 (pancreatic cell line) as FR-, and A549 (lung cancer cell line) having marginal FR expression. Complete selectivity of the FNPs towards the FR+ cell line was found. Quantification of PDT results by MTS assays and flow cytometry show that PDT treatment was fully selective to the FR+ cell line (OVCAR3). No cell mortality was observed for the other cell lines studied here within experimental error. Finally, the issue of confirming and quantifying small molecule drug delivery to diseased tissue was tackled by developing quantum dot (Qdot) biosensors with the aim of achieving fluorescence reporting of intracellular small molecule/drug delivery. For fluorescence reporting prior expertise in control of the fluorescence state of Qdots was employed, where redox active ligands can place the Qdot in a quenched OFF state. Ligand attachment was accomplished by disulfide linker chemistry. This chemistry is reversible in the presence of sulfur reducing biomolecules, resulting in Qdots in a brightly fluorescent ON state. Glutathione (GSH) is such a biomolecule that is present in the intracellular environment. Experimental in-vitro data shows that this design was successfully implemented.
Show less - Date Issued
- 2014
- Identifier
- CFE0005839, ucf:50923
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005839
- Title
- The Application of Chemometrics to the Detection and Classification of Ignitable Liquids in Fire Debris Using the Total Ion Spectrum.
- Creator
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Lewis, Jennifer, Sigman, Michael, Campiglia, Andres, Clausen, Christian, University of Central Florida
- Abstract / Description
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Current methods in ignitable liquid identification and classification from fire debris rely on pattern recognition of ignitable liquids in total ion chromatograms, extracted ion profiles, and target compound comparisons, as described in American Standards for Testing and Materials E1618-10. The total ion spectra method takes advantage of the reproducibility among sample spectra from the same American Society for Testing and Materials class. It is a method that is independent of the...
Show moreCurrent methods in ignitable liquid identification and classification from fire debris rely on pattern recognition of ignitable liquids in total ion chromatograms, extracted ion profiles, and target compound comparisons, as described in American Standards for Testing and Materials E1618-10. The total ion spectra method takes advantage of the reproducibility among sample spectra from the same American Society for Testing and Materials class. It is a method that is independent of the chromatographic conditions that affect retention times of target compounds, thus aiding in the use of computer-based library searching techniques. The total ion spectrum was obtained by summing the ion intensities across all retention times. The total ion spectrum from multiple fire debris samples were combined for target factor analysis. Principal components analysis allowed the dimensions of the data matrix to be reduced prior to target factor analysis, and the number of principal components retained was based on the determination of rank by median absolute deviation. The latent variables were rotated to find new vectors (resultant vectors) that were the best possible match to spectra in a reference library of over 450 ignitable liquid spectra (test factors). The Pearson correlation between target factors and resultant vectors were used to rank the ignitable liquids in the library. Ignitable liquids with the highest correlation represented possible contributions to the sample. Posterior probabilities for the ASTM ignitable liquid classes were calculated based on the probability distribution function of the correlation values. The ASTM ignitable liquid class present in the sample set was identified based on the class with the highest posterior probability value. Tests included computer simulations of artificially generated total ion spectra from a combination of ignitable liquid and substrate spectra, as well as large scale burns in 20'x8'x8' containers complete with furnishings and flooring. Computer simulations were performed for each ASTM ignitable liquid class across a range of parameters. Of the total number of total ion spectra in a data set, the percentage of samples containing an ignitable liquid was varied, as well as the percent of ignitable liquid contribution in a given total ion spectrum. Target factor analysis was them performed on the computer-generated sample set. The correlation values from target factor analysis were used to calculate posterior probabilities for each ASTM ignitable liquid class. Large scale burns were designed to test the detection capabilities of the chemometric approach to ignitable liquid detection under conditions similar to those of a structure fire. Burn conditions were controlled by adjusting the type and volume of ignitable liquid used, the fuel load, ventilation, and the elapsed time of the burn. Samples collected from the large scale burns were analyzed using passive headspace adsorption with activated charcoal strips and carbon disulfide desorption of volatiles for analysis using gas chromatography-mass spectrometry.
Show less - Date Issued
- 2011
- Identifier
- CFE0004477, ucf:49301
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004477
- Title
- Quantitative Assessment of the effects of Microbial Degradation of a Simple Hydrocarbon Mixture.
- Creator
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Kindell, Jessica, Sigman, Michael, Bridge, Candice, Campiglia, Andres, University of Central Florida
- Abstract / Description
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Ignitable liquids consist of either a single organic compound or a complex organic mixture. In regards to fire debris analysis, the analyst is responsible for determining if an ignitable liquid residue is present. However, when extracted from soil-containing fire debris evidence, chemical degradation from microorganisms is observed to result in the loss of compounds based on chemical structure. It can also happen when the evidence container is stored at room temperature before analysis. This...
Show moreIgnitable liquids consist of either a single organic compound or a complex organic mixture. In regards to fire debris analysis, the analyst is responsible for determining if an ignitable liquid residue is present. However, when extracted from soil-containing fire debris evidence, chemical degradation from microorganisms is observed to result in the loss of compounds based on chemical structure. It can also happen when the evidence container is stored at room temperature before analysis. This can present a challenge to the fire debris analyst when identifying and classifying the ignitable liquid residue based on the criteria established by standard test methods. The purpose of this research was to observe the microbial degradation of fourteen compounds, at room temperature over a period of time, for possible by-product formation that could coincide with compounds normally present in an ignitable liquid. Additionally, a quantitative assessment was performed to observe and record the loss rate of compounds in a representative simple mixture. Finally, the loss rate from the simple mixture was compared to commercially available ignitable liquids. Degradation studies were conducted to observe the microbial degradation of a representative compounds (individually and in a simple mixture, both weathered and unweathered) and seven ignitable liquids of different ASTM E1618 classifications. Potting soil was spiked with 20 (&)#181;L of a liquid/compound and was allowed to stand at room temperature for a period of time. The simple mixture was evaporated to 50% and 90% using a steady nitrogen gas flow to compare the degradation process to the unweathered mixture. All samples were extracted and analyzed using passive-headspace concentration and gas chromatography-mass spectrometry.The formation of by-products was not observed when degrading the compounds from the simple mixture individually as seen in other research. The simple mixture, unweathered and 50% weathered, resulted in rapid degradation of their oxygenated compounds. The straight-chained alkanes and toluene were observed to be more susceptible to microbial attack than the highly-substituted aromatics and the branched and cyclic alkanes. The 90% weathered mixture followed the same degradation trend as the unweathered and 50% weathered samples, although it only contained two compounds. The loss rates/half-lives for each simple mixture sample (unweathered, 50% weathered, and 90% weathered) were determined to be approximately 3.5, 3.5, and 0.84 days. The unweathered and 50% weathered sample half-lives were similar due to containing compounds with similar susceptibility to degradation, while the 90% weathered sample contained one compound that was more highly susceptible to degradation. When comparing the 3.5 day half-life to the seven different ASTM class liquids, the isoparaffinic product and the naphthenic-paraffinic product had similar rates of degradation while aromatic solvent and normal alkane classes had the shortest half-lives. When observing the degradation of the gasoline, medium petroleum distillate and the miscellaneous, the constituent compounds were seen to exhibit a range of degradation rates that corresponded to half-lives less than and greater than 3.5 days.
Show less - Date Issued
- 2015
- Identifier
- CFE0005966, ucf:50817
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005966
- Title
- Classification of Silicone-Based Personal and Condom Lubricants Using DART-TOFMS.
- Creator
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Harvey, Lauren, Bridge, Candice, Sigman, Michael, Campiglia, Andres, Yestrebsky, Cherie, University of Central Florida
- Abstract / Description
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Sexual lubricants are used to enable sexual encounters. There are different types of sexual lubricants such as water-based, oil-based, and silicone-based. They come pre-applied to condoms and separately in bottles as personal lubricants. Although sexual lubricants are intended for consensual use, they are also unfortunately used during the commission of sexual assaults. The analysis of sexual lubricants facilitates sexual assault investigations. With the increased usage of condoms in sexual...
Show moreSexual lubricants are used to enable sexual encounters. There are different types of sexual lubricants such as water-based, oil-based, and silicone-based. They come pre-applied to condoms and separately in bottles as personal lubricants. Although sexual lubricants are intended for consensual use, they are also unfortunately used during the commission of sexual assaults. The analysis of sexual lubricants facilitates sexual assault investigations. With the increased usage of condoms in sexual assault cases, the potential of collected DNA evidence in each case is reduced. In the absence of biological evidence, the presence of sexual lubricants after a sexual assault can provide an additional link between a suspect and the crime scene and/or victim. Having the ability to compare known and unknown sexual lubricants may be the only actionable information available for investigators. Current lubricant analysis only classifies samples into lubricant types based on the major component such as glycerol, petrolatum, and polydimethylsiloxane for water-based, oil-based, and silicone-based lubricants respectively. Differentiation within major types has not been explored. Previously, protocols have been developed to detect and categorize personal lubricants using Fourier transform infrared (FTIR) spectroscopy, gas chromatography-mass spectrometry (GC-MS), liquid chromatography mass spectrometry (LC-MS), and pyrolysis GC-MS. FTIR is routinely used as a screening tool to detect peaks of the major lubricant components and the mass spectrometry (MS) techniques are commonly used to confirm the presence of some of the major components, excluding PDMS.This thesis focused on the differentiation of silicone-based personal and condom lubricants because it is a common type of lubricant due to its ability to reduce friction for a longer period of time. Fifty-six (56) silicone personal and condom lubricants were analyzed to identify unique characteristics that can be used to determine individual sub-classes and test those sub-classes. Direct analysis in real time-time of flight mass spectrometry (DART-TOFMS) was utilized because minor and unique molecular ions that could be attributed to different sub-groups can easily be distinguished from the major sample peaks. This is primarily based on the direct mass spectrometry design of the instrumentation that can differentiate minor components from major components that might not be observed using traditional chromatographic separation. The DART source creates molecular ions for individual components in mixed samples under atmospheric conditions in either positive or negative mode. The TOF-MS, which is capable of high resolution and accurate mass analysis, allows more accurate and precise detection of molecular component ions. Additionally, no sample preparation is required to analyze neat samples, which minimizes potential contamination issues. Attenuated total reflectance-FTIR (ATR-FIR) was used to analyze the training set personal lubricants to compare previous methods of analysis to the newly developed DART-TOFMS method of analysis.Principle component analysis (PCA) and cluster analysis were used to identify potential sub-groups and subsequently a classification scheme. Linear discriminant analysis was utilized to conduct leave one out cross validation and to categorize test samples. Eight sub-groups were developed based on the presence and/or absence of PDMS and minor component peaks observed.A classification scheme was developed using the eight sub-groups identified through PCA and cluster analysis. This classification scheme was tested using LDA to classify blind samples. One group includes a scented personal lubricant. Another group includes flavored condom lubricants. The other groups were developed based on the relative intensity of PDMS peaks and minor component peaks. Variation of the intensity of PDMS peaks between and within samples of different lot numbers causes some misclassification of samples. This classification scheme also doesn't take into account real-world factors such as dilution and biodegradation. Although further research is required to create a more stable classification scheme, the identified sub-groups are a good foundation for the creation of a lubricant database and finalized classification scheme.
Show less - Date Issued
- 2016
- Identifier
- CFE0006459, ucf:51415
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006459
- Title
- Conformations and Dynamics of Semi-Flexible Polymers.
- Creator
-
Huang, Aiqun, Bhattacharya, Aniket, Kokoouline, Viatcheslav, Tatulian, Suren, Campiglia, Andres, University of Central Florida
- Abstract / Description
-
In this dissertation, we investigate the conformations, transverse fluctuations and dynamics of two-dimensional (2D) semi-flexible polymers both in the bulk and under channel confinement. We present unified scaling relations in regard to various quantities of interest for a broad range of combinations of chain length and chain stiffness using Langevin dynamics simulation. We also present a three-dimensional (3D) heterogeneous semi-flexible chain model for a double stranded DNA (dsDNA). Our...
Show moreIn this dissertation, we investigate the conformations, transverse fluctuations and dynamics of two-dimensional (2D) semi-flexible polymers both in the bulk and under channel confinement. We present unified scaling relations in regard to various quantities of interest for a broad range of combinations of chain length and chain stiffness using Langevin dynamics simulation. We also present a three-dimensional (3D) heterogeneous semi-flexible chain model for a double stranded DNA (dsDNA). Our model not only confirms the established findings for homogeneous dsDNA, but also predicts new physical phenomenon for heterogeneous dsDNA. The problems studied in this dissertation are relevant to analysis of the conformations and dynamics of biopolymers (such as DNA) in living organisms, and also offer insights for developing devices which operate on the single-molecule level.In particular, we present a unified description for the dynamics of building-blocks (monomers) of a semi-flexible chain. We consider the full range of flexibility from the case where the chain is fully flexible (no stiffness at all) to the case where the chain behaves like a rod (infinite stiffness). Our theory predicts qualitatively different sub-diffusive regimes for the monomer dynamics originating from the chain stiffness by studying the mean square displacement (MSD) of the monomers before the chain dynamics become purely diffusive.For the conformations in the bulk, we present results confirmed and agreed by two completely different models of semi-flexible polymers, with one of which is the bead-spring model (studied by Langevin dynamics) in the continuum space, the other (studied by Monte Carlo) is a self-avoiding walk chain on the square lattice, where only discrete bond angles are possible. We point out the universal features of chain conformations and fluctuations which are independent of the models.For the conformations under channel confinement, we discover qualitatively different conformations and dynamics of the chain as a function of the channel width and chain stiffness, and show how globule like shapes ((")de Gennes blobs(")) for more flexible chains continuously go over to shapes in the form of deflections from the wall ((")Odijk limit(")) for more stiff chains. We provide theoretical arguments how these regimes occur and interpolate among each other as one varies different parameters of the model. We also demonstrate the effect of physical dimensions (either 2D or 3D) on these regimes and argue that since in 2D the excluded volume (EV) effect is more severe compared to 3D, certain regimes do not exist in 2D.Finally, we study a model of a dsDNA , where both base-pairing and base-stacking interactions are accounted for albeit at a low computational cost compared to the other existing models. Our model correctly recovers the stiffness for dsDNA and ssDNA at different temperatures. Under most conditions of interest, a dsDNA can locally denature and form bubbles due to thermal fluctuations. At a critical temperature, a dsDNA undergoes a phase transition, in which the two strands of dsDNA completely melt to two single strands (two ssDNA). By considering EV interactions and calculating the bubble size distribution, recent studies have shown that this denaturation process is a first order transition. We show that for a homogeneous dsDNA made of only AT or GC pairs, our simulation results agree with the previous conclusion of first order transition, however, for sequences of periodic AT and GC regions, when the periodic size is relatively large compared to the sequence length, we show that the bubble size distribution exhibits peaks expressing the sequence pattern, and more importantly, the denaturation is no longer a first order transition.All these studies reported in the dissertation are relevant to the physics of living systems.
Show less - Date Issued
- 2016
- Identifier
- CFE0006464, ucf:51429
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006464
- Title
- Characterization of Post-Fire Priming Cup Residue Using Scanning Electron Microscopy Coupled With Energy Dispersive X-Ray Spectrometry.
- Creator
-
Terry, Molly, Bridge, Candice, Sigman, Michael, Campiglia, Andres, University of Central Florida
- Abstract / Description
-
Ammunition is most often comprised of a lead-based priming mixture which contributes to the traditional characteristics of gunshot residue (GSR). Due to the health risks often associated with lead, lead-free primer alternatives are becoming increasingly more popular. Thus, it is becoming more difficult to determine the presence of GSR based on traditional means, i.e. the presence of lead (Pb), barium (Ba), and antimony (Sb). Eight different ammunitions were purchased which consisted of one...
Show moreAmmunition is most often comprised of a lead-based priming mixture which contributes to the traditional characteristics of gunshot residue (GSR). Due to the health risks often associated with lead, lead-free primer alternatives are becoming increasingly more popular. Thus, it is becoming more difficult to determine the presence of GSR based on traditional means, i.e. the presence of lead (Pb), barium (Ba), and antimony (Sb). Eight different ammunitions were purchased which consisted of one lead-based and one lead-free from four different manufacturers, including Winchester, Federal, Liberty, and Sellier (&) Bellot. Half of the rounds from each manufacturer and chemical composition (i.e. lead-based or lead-free) were disassembled, e.g. the projectile and smokeless powder were removed, leaving the priming cup in place (i.e. primed only). The remaining cartridges were left intact (i.e. full cartridge). Both the full cartridges and the primed only cartridges for each ammunition were fired using a 9mm Glock and the cartridges were collected post-fire, and subsequently deprimed. Five cups and five anvils from each type of ammunition were adhered to aluminum stubs via colloidal graphite. The GSR remaining on the anvils and in the cups was then analyzed using scanning electron microscopy coupled with energy dispersive x-ray spectrometry (SEM-EDX). Three spectra were collected for each anvil and each cup resulting in 30 total spectra per type of ammunition. The primary element peaks were then selected and four different dataset matrices were created for the full cartridge anvils, full cartridge cups, primed only anvils, and primed only cups. The data was processed using unit vector normalization and was then analyzed using principal component analysis (PCA) and linear discriminant analysis (LDA) to determine the characterization between lead-free and lead-based ammunition. The anvils provided better separation and characterization based on the ability to better collect x-rays, and therefore demonstrated the capability of the ammunition to cluster by both primer mixture composition and manufacturer. The lead-based and lead-free primers showed consistencies across samples, such as the presence or absence of K, which allowed for characterization based on primer composition.
Show less - Date Issued
- 2016
- Identifier
- CFE0006509, ucf:51377
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006509
- Title
- Optimizing Laboratory Pyrolysis Methods to Compliment Real World Fire Debris.
- Creator
-
Coulson, Richard, Sigman, Michael, Bridge, Candice, Yestrebsky, Cherie, Campiglia, Andres, University of Central Florida
- Abstract / Description
-
Forensic analysts are tasked with determining the presence of ignitable liquid residue in fire debris. Analysis of fire debris allows the analyst to understand how the fire occurred. However, the presence of some substrates can potentially impact the identification of ignitable liquid residue and classification of a sample as positive or negative for the presence of ignitable liquid. Pyrolysis of building materials and furnishings (substrates) lead to background interference within the...
Show moreForensic analysts are tasked with determining the presence of ignitable liquid residue in fire debris. Analysis of fire debris allows the analyst to understand how the fire occurred. However, the presence of some substrates can potentially impact the identification of ignitable liquid residue and classification of a sample as positive or negative for the presence of ignitable liquid. Pyrolysis of building materials and furnishings (substrates) lead to background interference within the resulting chromatographic profile. To combat misclassification of a sample as positive for ignitable liquid residue, knowledge of the pyrolysis products from individual substrates is of utmost importance. However, unburned reference samples from a fire scene can be difficult to obtain. The use of a database in conjunction with the analysis of the samples can lead to a more complete analysis of fire debris. Within this research, four different burn methods (modified destruction distillation method, top heat, bottom heat, and tube furnace) were utilized in burning eight different flooring substrates (polyester, nylon, and olefin carpeting, carpet padding, vinyl flooring, laminate flooring, yellow pine, and plywood) to obtain pyrolysis/combustion product profiles. Each burn method was performed at three different burn times for a total of twelve different burns of each substrate. Standard methods, ASTM E1412-12 and ASTM E1618-14, were used in the extraction and interpretation of the laboratory burn products. Principal component analysis (PCA) was used to relate the laboratory burn results to neat ignitable liquid/substrate and large scale burn data sets.Laboratory burn data projected into the PCA space displayed that the laboratory burn data is similar to the data contained within the ILRC and Substrate databases. Differences observed within laboratory burn data projections illustrated the variability of the laboratory burn methods. The composition of the substrate dictated the pyrolysis/combustion products produced. While this research only focuses on flooring substrates, an increase in the number of different types of materials in the Substrate Database can aid analysts in identifying common pyrolysis/combustion products observed in fire debris.
Show less - Date Issued
- 2017
- Identifier
- CFE0006578, ucf:51357
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006578
- Title
- A Universal Electrochemical Biosensor for the Detection of Nucleic Acids based on a Four-Way Junction Structure.
- Creator
-
Mills, Dawn, Chumbimuni Torres, Karin, Kolpashchikov, Dmitry, Campiglia, Andres, Dupras, Tosha, Tetard, Laurene, University of Central Florida
- Abstract / Description
-
Electrochemical hybridization sensors have been explored extensively for analysis of specific nucleic acids. However, commercialization of the platform is hindered by the need for attachment of separate oligonucleotide probes complementary to a RNA or DNA target to an electrode's surface. This dissertation demonstrates that a single probe can be used to analyze several nucleic acid targets of different lengths with high selectivity, low cost and can be regenerated in 30 seconds by a simple...
Show moreElectrochemical hybridization sensors have been explored extensively for analysis of specific nucleic acids. However, commercialization of the platform is hindered by the need for attachment of separate oligonucleotide probes complementary to a RNA or DNA target to an electrode's surface. This dissertation demonstrates that a single probe can be used to analyze several nucleic acid targets of different lengths with high selectivity, low cost and can be regenerated in 30 seconds by a simple water rinse. The universal electrochemical four-way junction (4J)-forming (UE4J) sensor consists of a universal DNA stem-loop (USL) probe attached to the electrode's surface and two adaptor strands (m and f) which hybridize to the USL probe and the analyte to form a 4J structure. The UE4J sensor enables a high selectivity by recognition of a single base substitution, even at room temperature. The sensor was monitored with voltammetry and electrochemical impedance spectroscopy using different redox labeling strategies and optimized using synthetic nucleic acid sequences. After the sensor was optimized and fully characterized, it was modified for the detection of the Zika virus. The UE4J sensor presented here opens a venue for a re-useable universal platform that can be adopted at low cost for the analysis of potentially any DNA or RNA targets.
Show less - Date Issued
- 2017
- Identifier
- CFE0007290, ucf:52146
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007290
- Title
- Time-Resolved Phosphorescence Spectroscopy at Cryogenic Temperatures for the Environmental Analysis of Polycyclic Aromatic Sulfur Heterocycles in Oil Contaminated Sites.
- Creator
-
Al Tameemi, Maha, Campiglia, Andres, Zou, Shengli, Harper, James, Heider, Emily, Coffey, Kevin, University of Central Florida
- Abstract / Description
-
The large volume of crude oil released into the Gulf of Mexico by the Deepwater Horizon (DWH) accident has raised considerable concerns over potential ecosystem impacts. The dispersion of harmful oil components into the ocean waters could pose long term risks to flora and fauna. Due to the complexity of oil contaminated sites, the unambiguous identification and quantitation of environmental pollutants often requires the sequence of high-performance liquid chromatography (HPLC) and gas...
Show moreThe large volume of crude oil released into the Gulf of Mexico by the Deepwater Horizon (DWH) accident has raised considerable concerns over potential ecosystem impacts. The dispersion of harmful oil components into the ocean waters could pose long term risks to flora and fauna. Due to the complexity of oil contaminated sites, the unambiguous identification and quantitation of environmental pollutants often requires the sequence of high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). A classic example is the analysis of the sixteen polycyclic aromatic hydrocarbons included in the priority pollutants list of the U.S. Environmental Protection Agency (EPA-PAHs).This dissertation tackles a different aspect of environmental analysis as is focuses on the photoluminescence spectroscopy of polycyclic aromatic sulfur heterocycles (PASHs). Since considering the EPA-PAHs alone can lead to drastic underestimations of potential toxic effects of oil spills, a strong case can be made for including hetero-aromatic compounds in risk assessments of contaminated sites. PASHs exist in an even greater variety of chemical structures than PAHs and, because of the asymmetry imposed by the heteroatom, the number of PASHs isomers is usually large. The existence of numerous isomers of the same molecular weight increases the difficulty of separation and identification by chromatographic methods.This dissertation demonstrates the capability to differentiate individual PASHs isomers of MW 234 g mol-1 via vibrational spectroscopy at liquid nitrogen (77 K) and liquid helium (4.2K) temperatures. Fluorescence and phosphorescence spectra are presented for isomer determination at the parts-per-billion (ng. mL-1) concentration levels. It is demonstrated that the relatively long phosphorescence decays of PASHs facilitate the time discrimination of strong fluorescence.interference from PAHs and methylated-PAHs often present in Normal-Phase HPLC fractions. The spectral and lifetime databases compiled in this dissertation have paved the road to explore the full dimensionality of photoluminescence spectroscopy.
Show less - Date Issued
- 2017
- Identifier
- CFE0007275, ucf:52183
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007275
- Title
- Detection of Mercury Through Surface Plasmon Resonance of Immobilized Gold Nanorods.
- Creator
-
Trieu, Khang, Campiglia, Andres, Rex, Matthew, Heider, Emily, Frazer, Andrew, Harper, James, Bhattacharya, Aniket, University of Central Florida
- Abstract / Description
-
Mercury is a known environmental pollutant that can damage the brain, heart, kidney and lungs upon exposure. Emissions from fossil fuel plants can release mercury into the air, where it can settle into the water supply and be exposed to human and aquatic life. The use of gold nanorods functionalized on solid substrates as a mercury sensor in tap water samples is investigated herein. The functionalization of the substrates involves the physical immobilization of the nanorods onto the solid...
Show moreMercury is a known environmental pollutant that can damage the brain, heart, kidney and lungs upon exposure. Emissions from fossil fuel plants can release mercury into the air, where it can settle into the water supply and be exposed to human and aquatic life. The use of gold nanorods functionalized on solid substrates as a mercury sensor in tap water samples is investigated herein. The functionalization of the substrates involves the physical immobilization of the nanorods onto the solid surface through the use of (3-mercaptopropyl)trimethoxysilane (MPTMS). The immobilization of the nanorods drastically increases their stability, allowing for use in complicated sample matrices. When gold nanorods are exposed to mercury in aqueous samples, their amalgamation to mercury metal causes a reduction of the effective aspect ratio of the nanoparticles and a blue shift of their maximum longitudinal surface plasmon resonance (SPR) absorption wavelength. Quantitative analysis is made possible due to the linear correlation that exists between the concentration of mercury and the wavelength shift of the maximum SPR absorption wavelength. In order to achieve the quantitative amalgamation of Hg (II) with the nanorods, it is necessary to reduce the mercury ions to mercury metal, which is accomplished herein via chemical or electrochemical processes. Chemical reduction of mercury was been carried out with a strong reducing agent, specifically sodium borohydride. Electrochemical reduction has been accomplished with gold nanorods immobilized on Indium Tin Oxide (ITO) substrates. Mercury determination in tap water using the immobilized gold nanorods was successfully conducted, with further experiments on improving selectivity with potential control, and improving sensitivity through flow injection analysis.
Show less - Date Issued
- 2019
- Identifier
- CFE0007544, ucf:52604
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007544
- Title
- A deoxyribozyme sensor and isothermal amplification for human sex determination.
- Creator
-
Smith, Alexandra, Kolpashchikov, Dmitry, Campiglia, Andres, Harper, James, Beazley, Melanie, Tetard, Laurene, University of Central Florida
- Abstract / Description
-
Ribozymes are known to catalyze biochemical reactions and behave like enzymes. They are naturally occurring and have very diverse functions within a cell. After investigating ribozymes that next step was to find if DNA can exhibit the same characteristics since RNA and DNA only differ by a ribose 2'-hydroxyl group. This evolution in curiosity gave rise to artificial DNA enzymes that can catalyze certain reactions and have been created by in vitro selection methods. Due to the ability to...
Show moreRibozymes are known to catalyze biochemical reactions and behave like enzymes. They are naturally occurring and have very diverse functions within a cell. After investigating ribozymes that next step was to find if DNA can exhibit the same characteristics since RNA and DNA only differ by a ribose 2'-hydroxyl group. This evolution in curiosity gave rise to artificial DNA enzymes that can catalyze certain reactions and have been created by in vitro selection methods. Due to the ability to manipulate and control DNA hybridization, the deoxyribozyme is advantageous to the field of molecular diagnostics. Other hybridization probes like Taqman for PCR (polymerase chain reaction) or a molecular beacon are more conventional methods for molecular diagnostics, but deoxyribozyme-based nucleic acid sensors are overall more sensitive due to their catalytic enhancement of a signal and more selective due to structural design. When the deoxyribozyme is split into two probes, it is very efficient in identifying a minute difference in sequence compared to the monolith structure. This binary deoxyribozyme sensor (BiDz) has two probes, each containing an analyte binding arm, substrate binding arm, and half of the catalytic core. The monolith structure, known as a catalytic molecular beacon (CMB), contains a hairpin that contains the analyte binding arm in the loop and the substrate binding arms in the stem. The catalytic core is fully intact but deemed inactive due to the substrate binding arms being complimentary to an inhibitory sequence forming the stem. Once the sensor binds the analyte, catalytic core is formed/activated and cleaves a substrate containing a fluorophore and quencher. When the substrate is cleaved a fluorescent signal is given off denoting the detection of the target DNA. Deoxyribozyme sensors can be applied to the field of human sex determination by detecting the Amelogenin gene. Found on both sex chromosomes, the Amelogenin gene is the most common marker used for sex determination because it exhibits dimorphism in length and sequence. Sex identification from ancient skeletal remains is crucial to understanding the social structure of our history. When conventional methods, such as metric analysis, are not an option due to the fragmented or prepubescent remains, molecular diagnostics are needed. Amplification of DNA is required to be able to detect the target sequence in human samples. Isothermal loop-mediated amplification (LAMP) is a fast and simple technique that provides ample amounts of amplicon. It is advantageous over PCR because it amplifies at one temperature and no thermal cycler is needed. Two different sensors have been designed to detect the X and Y specific sequences with high selectivity. From a direct comparison between the CMB and BiDZ, the binary structure has shown to be simpler and less expensive to design, and highly selective toward single base substitutions (SNS). While both sensors contain detection limits in the picomolar range, which is consistent with data published by other research groups, the CMB sensors failed to function at higher temperatures (55oC). BiDz sensors are shown to be superior to the CMB design, particularly when selectivity based analysis is desired. For human sex determination, the binary sensor detected sex specific sequences with great selectivity. The sensor then detected LAMP amplified DNA from male and female teeth after 30 minutes of amplification. Combining a binary deoxyribozyme sensor and isothermal amplification can provide a new and valuable method for human sex determination.
Show less - Date Issued
- 2017
- Identifier
- CFE0007133, ucf:52306
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007133
- Title
- Advancements in Liquid Chromatography for the Determination of Polycyclic Aromatic Compounds in Environmental Samples.
- Creator
-
Hayes, Hugh, Campiglia, Andres, Harper, James, Yestrebsky, Cherie, Frazer, Andrew, Coffey, Kevin, University of Central Florida
- Abstract / Description
-
The purpose of this dissertation is to provide a new and improved analytical methodology for the analysis of polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic sulfur heterocycles (PASHs) in environmental samples. Hundreds of PAHs and PASHs are present in the environment and have great toxicological importance and the chemical determination of these components is a priority. The complete normal-phase liquid chromatography (NPLC) retention behavior has been explored for these...
Show moreThe purpose of this dissertation is to provide a new and improved analytical methodology for the analysis of polycyclic aromatic hydrocarbons (PAHs) and polycyclic aromatic sulfur heterocycles (PASHs) in environmental samples. Hundreds of PAHs and PASHs are present in the environment and have great toxicological importance and the chemical determination of these components is a priority. The complete normal-phase liquid chromatography (NPLC) retention behavior has been explored for these compounds. Retention indices were determined for 124 PAHs, 62 methyl-PAHs (MePAHs), 67 PASHs, and 80 alkyl-PASHs on an aminopropyl (NH2) stationary phase which represents the most comprehensive study of polycyclic aromatic compounds in normal phase conditions to date. NPLC retention behavior for PAHs and PASHs directly correlated to the total number of aromatic carbons in the parent structures. The normal-phase retention behavior information was used to develop an NPLC fractionation procedure to aid in the sample cleanup for complex environmental matrices which can later be analyzed by gas chromatography/mass spectrometry (GC/MS). Standard Reference Material (SRM) 1597a (complex mixture of PAHs in coal tar), SRM 1991 (coal tar/petroleum extract), and SRM 1975 (diesel particulate extract) were analyzed before and after NPLC fractionation by using GC/MS. In SRM 1597a, the NPLC-GC/MS method allowed for the identification of 72 PAHs, 56 Me-PAHs, 35 PASHs, and 59 alkyl-PASHs. The NPLC-GC/MS procedure also provided the tentative identification of 74 PAHs and 117 MePAHs based on the molecular ion peak only. Furthermore, this method allowed for the following identification breakdown: SRM 1991(-)31 PASHs and 58 alkyl-PASHs; and SRM 1975(-)13 PASHs and 25 alkyl-PASHs.Additional work related to the NPLC fractionation of SRM 1597 included the collection of room-temperature fluorescence spectra for the 21 PAHs with molecular mass (MM) 302 Da known to be in SRM 1597a during reversed-phase liquid chromatography (RPLC) separation. Adding spectral features to a chromatographic run provided the tentative identification of 20 PAHs based on retention times and the presence of 18 were confirmed on the basis of spectral profiles. The advancements in liquid chromatography presented in this dissertation via NPLC fractionation along with RPLC stop-flow fluorescence spectra collection shows potential for becoming routine methodologies for PAC determination in complex environmental samples.
Show less - Date Issued
- 2018
- Identifier
- CFE0007190, ucf:52244
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007190
- Title
- Quantitative Line Assignment in Optical Emission Spectroscopy.
- Creator
-
Chappell, Jessica, Baudelet, Matthieu, Hernandez, Florencio, Campiglia, Andres, Ni, Liqiang, Sigman, Michael, University of Central Florida
- Abstract / Description
-
Quantitative elemental analysis using Optical Emission Spectroscopy (OES) starts with a high level of confidence in spectral line assignment from reference databases. Spectral interferences caused by instrumental and line broadening decrease the resolution of OES spectra creating uncertainty in the elemental profile of a sample for the first time. An approach has been developed to quantify spectral interferences for individual line assignment in OES. The algorithm calculates a statistical...
Show moreQuantitative elemental analysis using Optical Emission Spectroscopy (OES) starts with a high level of confidence in spectral line assignment from reference databases. Spectral interferences caused by instrumental and line broadening decrease the resolution of OES spectra creating uncertainty in the elemental profile of a sample for the first time. An approach has been developed to quantify spectral interferences for individual line assignment in OES. The algorithm calculates a statistical interference factor (SIF) that combines a physical understanding of plasma emission with a Bayesian analysis of the OES spectrum. It can be used on a single optical spectrum and still address individual lines. Contrary to current methods, quantification of the uncertainty in elemental profiles of OES, leads to more accurate results, higher reliability and validation of the method. The SIF algorithm was evaluated for Laser-Induced Breakdown Spectroscopy (LIBS) on samples with increasing complexity: from silicon to nickel spiked alumina to NIST standards (600 glass series and nickel-chromium alloy). The influence of the user's knowledge of the sample composition was studied and showed that for the majority of spectral lines this information is not changing the line assignment for simple compositions. Nonetheless, the amount of interference could change with this information, as expected. Variance of the SIF results for NIST glass standard was evaluated by the chi-square hypothesis test of variance showing that the results of the SIF algorithm are very reproducible.
Show less - Date Issued
- 2018
- Identifier
- CFE0007564, ucf:52575
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007564
- Title
- Use of an Activated Magnesium/cosolvent System for the Desorption and Degradation of Polycyclic Aromatic Hydrocarbons and Their Oxygenated Derivatives in Contaminated Soils.
- Creator
-
Elie, Marc, Yestrebsky, Cherie, Clausen, Christian, Elsheimer, Seth, Campiglia, Andres, Randall, Andrew, University of Central Florida
- Abstract / Description
-
The contamination of soils, with polycyclic aromatic hydrocarbons (PAHs), remains a widespread environmental concern. In the past two decades, many physical, chemical and biological methods have been developed and evaluated for the degradation of PAHs. However, due to their low aqueous solubility, high sorption affinity, hydrophobicity and recalcitrance, the environmental remediation of PAHs in soil continues to be economically challenging. In addition to PAH contamination, the presence of...
Show moreThe contamination of soils, with polycyclic aromatic hydrocarbons (PAHs), remains a widespread environmental concern. In the past two decades, many physical, chemical and biological methods have been developed and evaluated for the degradation of PAHs. However, due to their low aqueous solubility, high sorption affinity, hydrophobicity and recalcitrance, the environmental remediation of PAHs in soil continues to be economically challenging. In addition to PAH contamination, the presence of oxygenated derivatives of PAHs (OPAHs), in soils, has increasingly become a concern due to their greater toxic properties compared to parent PAH compounds. To date, no investigations on OPAH-remediation methods have been presented in the literature. The use of zero-valent metals (ZVMs) has been reported for several halogenated contaminants in solution systems, but the effectiveness of ZVM to degrade sorbed PAHs and OPAHs has been rarely addressed. This present research focuses on the development of a combined technique for the feasible desorption and degradation of PAHs and OPAHs in soils. PAH and OPAH degradation efficiency, using activated magnesium (Mg) metal combined with an ethanol-ethyl lactate cosolvent (1:1 ratio), was initially examined in soil-free systems. This metal/cosolvent system demonstrated adequate degradation (above 80%) for high-molecular-weight (HMW) PAHs, which were subsequently converted into hydroaromatic compounds; while OPAHs were degraded and converted into hydroxylated or hydrogenated derivatives. Further soil-free studies revealed that the degradation rate was affected by the surface or reactive sites of the metal and that optimum degradation efficiency were obtained with Mg ball milled with graphite (Mg/C).In a bench-scale feasibility test, the efficacy of this system was assessed on a soil spiked with a mixture of three HMW PAHs compounds and three OPAHs compounds with amounts ranging from 0.033 mmol to 0.060 mmol. The experimental results show that 2 mL of an ethanol-ethyl lactate solvent mixture resulted in 58% to 85% extraction efficiency for the selected contaminants in 1 g of spiked soil, followed by 64 - 87% degradation efficiency of the extracted contaminants with 4.11 mmol of the activated metal. This activated-Mg/cosolvent system can be considered as a promising alternative method for ex situ remediation of PAH and OPAH-contaminated soils.
Show less - Date Issued
- 2012
- Identifier
- CFE0004533, ucf:49259
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004533
- Title
- Chemometric Applications to a Complex Classification Problem: Forensic Fire Debris Analysis.
- Creator
-
Waddell, Erin, Sigman, Michael, Belfield, Kevin, Campiglia, Andres, Yestrebsky, Cherie, Ni, Liqiang, University of Central Florida
- Abstract / Description
-
Fire debris analysis currently relies on visual pattern recognition of the total ion chromatograms, extracted ion profiles, and target compound chromatograms to identify the presence of an ignitable liquid according to the ASTM International E1618-10 standard method. For large data sets, this methodology can be time consuming and is a subjective method, the accuracy of which is dependent upon the skill and experience of the analyst. This research aimed to develop an automated classification...
Show moreFire debris analysis currently relies on visual pattern recognition of the total ion chromatograms, extracted ion profiles, and target compound chromatograms to identify the presence of an ignitable liquid according to the ASTM International E1618-10 standard method. For large data sets, this methodology can be time consuming and is a subjective method, the accuracy of which is dependent upon the skill and experience of the analyst. This research aimed to develop an automated classification method for large data sets and investigated the use of the total ion spectrum (TIS). The TIS is calculated by taking an average mass spectrum across the entire chromatographic range and has been shown to contain sufficient information content for the identification of ignitable liquids. The TIS of ignitable liquids and substrates, defined as common building materials and household furnishings, were compiled into model data sets. Cross-validation (CV) and fire debris samples, obtained from laboratory-scale and large-scale burns, were used to test the models. An automated classification method was developed using computational software, written in-house, that considers a multi-step classification scheme to detect ignitable liquid residues in fire debris samples and assign these to the classes defined in ASTM E1618-10. Classifications were made using linear discriminant analysis, quadratic discriminant analysis (QDA), and soft independent modeling of class analogy (SIMCA). Overall, the highest correct classification rates were achieved using QDA for the first step of the scheme and SIMCA for the remaining steps. In the first step of the classification scheme, correct classification rates of 95.3% and 89.2% were obtained for the CV test set and fire debris samples, respectively. Correct classifications rates of 100% were achieved for both data sets in the majority of the remaining steps which used SIMCA for classification. In this research, the first statistically valid error rates for fire debris analysis have been developed through cross-validation of large data sets. The error rates reduce the subjectivity associated with the current methods and provide a level of confidence in sample classification that does not currently exist in forensic fire debris analysis.
Show less - Date Issued
- 2013
- Identifier
- CFE0004954, ucf:49586
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004954