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ANALYTICAL EVALUATION OF THE FLUORESCENCE CHARACTERISTICS OF METABOLITES OF POLYCYCLIC AROMATIC HYDROCARBONS AT ROOM, LIQUID NITROGEN AND LIQUID HELIUM TEMPERATURES
Title
ANALYTICAL EVALUATION OF THE FLUORESCENCE CHARACTERISTICS OF METABOLITES OF POLYCYCLIC AROMATIC HYDROCARBONS AT ROOM, LIQUID NITROGEN AND LIQUID HELIUM TEMPERATURES.
Creator
Vatsavai, Keerthika, Campiglia, Andres, University of Central Florida
Abstract / Description
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
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Date Issued
2007
Identifier
CFE0001946, ucf:47461
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001946
Use of an Activated Magnesium/cosolvent System for the Desorption and Degradation of Polycyclic Aromatic Hydrocarbons and Their Oxygenated Derivatives in Contaminated Soils
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.
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Date Issued
2012
Identifier
CFE0004533, ucf:49259
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004533
Solid Phase Extraction Room Temperature Fluorescence Spectroscopy for the Direct Quantification of Monohydroxy Metabolites of Polycyclic Aromatic Hydrocarbons in Urine Samples
Title
Solid Phase Extraction Room Temperature Fluorescence Spectroscopy for the Direct Quantification of Monohydroxy Metabolites of Polycyclic Aromatic Hydrocarbons in Urine Samples.
Creator
Calimag, Korina Jesusa, Campiglia, Andres, Belfield, Kevin, Yestrebsky, Cherie, Chumbimuni Torres, Karin, Schulte, Alfons, University of Central Florida
Abstract / Description
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 identifi(&)#172;cation 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 HPLC1 and Laser-Excited Time-Resolved Shpol'skii Spectroscopy (LETRSS).2 The same concept is then extended to the analysis of monohydroxy-PAH in urine samples via SPE- HPLC3 and In-Capillary SPNE-CE.4 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.5 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 benzo[a]pyrene metabolites in alcohol matrixes.
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Date Issued
2013
Identifier
CFE0005141, ucf:50693
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005141
NOVEL IMPROVEMENTS ON THE ANALYTICAL CHEMISTRY OF POLYCYCLIC AROMATIC HYDROCARBONS AND THEIR METABOLITES
Title
NOVEL IMPROVEMENTS ON THE ANALYTICAL CHEMISTRY OF POLYCYCLIC AROMATIC HYDROCARBONS AND THEIR METABOLITES.
Creator
Wang, Huiyong, Campiglia, Andres, University of Central Florida
Abstract / Description
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.
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Date Issued
2010
Identifier
CFE0003202, ucf:48579
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003202
PHYSICOCHEMICAL AND THERMOCHEMICAL PROPERTIES OF SULFONATED POLY(ETHERETHERKETONE) ELECTROLYTE MEMBRANES
Title
PHYSICOCHEMICAL AND THERMOCHEMICAL PROPERTIES OF SULFONATED POLY(ETHERETHERKETONE) ELECTROLYTE MEMBRANES.
Creator
Rhoden, Stephen, Diaz, Diego, University of Central Florida
Abstract / Description
Fuel cells have long been seen as an alternative to combustion powered and diesel powered engines and turbines. Production of energy via a fuel cell conversion method can generate up to 60% efficiency in comparison to 30% using a combustion powered engine, with low co-production of harmful side-products. The polymer electrolyte membrane (PEM) adapted for the fuel cell application is one of the main components that determines the overall efficiency. This research project was focused towards...
Show moreFuel cells have long been seen as an alternative to combustion powered and diesel powered engines and turbines. Production of energy via a fuel cell conversion method can generate up to 60% efficiency in comparison to 30% using a combustion powered engine, with low co-production of harmful side-products. The polymer electrolyte membrane (PEM) adapted for the fuel cell application is one of the main components that determines the overall efficiency. This research project was focused towards novel PEMs, such as sulfonated poly(etheretherketone) or SPEEK, which are cost-efficient and robust with high proton conductivities under hydrated conditions. The degree of sulfonation (DS) of a particular SPEEK polymer determines the proton conducting ability, as well as the long term durability. For SPEEK with high DS, the proton conduction is facile, but the mechanical stability of the polymer decreases almost proportionally. While low DS SPEEK does not have sufficient sulfonic acid density for fast proton conduction in the membrane, the membrane keeps its mechanical integrity under fully saturated conditions. The main purpose of this work was to address both issues encountered with SPEEK sulfonated to low and high DS. The addition of both solid acids and synthetic cross-links were studied to address the main downfalls of the respective SPEEK polymers. Optimization of these techniques led to increased understanding of PEMs and notably better electrochemical performance of these fuel cell materials. Oxo-acids such as tungsten (VI) oxide (WO3) and phosphotungstic acid (PTA) have been identified as candidate materials for creating SPEEK composite membranes. The chemistry of these oxo-acids is well known, with their use as highly acidic catalyst centers adopted for countless homogeneous and heterogeneous, organic and inorganic reactions. Uniform dispersion of WO3 hydrate in SPEEK solution was done by a sol-gel process in which the filler particles were grown in an ionomer solution, cast and allowed to dry. PTA composites were made by adding the solid acid directly to a solution of the ionomer and casting. The latter casting was allowed to dry and Cs+- exchanged to stabilize the PTA from dissolution and leaching from the membrane. The chemical and physical properties of these membranes were characterized and evaluated using mainly conductometric and X-ray photoelectron spectroscopic methods. Composite SPEEK/ PTA membranes showed a 50% decrease in PEM resistance under hydrogen fuel cell testing conditions, while SPEEK/ WO3 composites demonstrated a ten-fold increase in the membrane's in-plane proton conductivity. The chemical and physical properties of these composites changed with respect to their synthesis and fabrication procedures. This study will expound upon their relations.
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Date Issued
2010
Identifier
CFE0003470, ucf:48976
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003470
On the Capillary Electrophoresis of Monohydroxy Metabolites of Polycyclic Aromatic Hydrocarbons and its Application to the Analysis of Biological Matrices
Title
On the Capillary Electrophoresis of Monohydroxy Metabolites of Polycyclic Aromatic Hydrocarbons and its Application to the Analysis of Biological Matrices.
Creator
Knobel, Gaston, Campiglia, Andres, Clausen, Christian, Belfield, Kevin, Liao, Yi, Bhattacharya, Aniket, University of Central Florida
Abstract / Description
Polycyclic aromatic hydrocarbons (PAH) are a class of environmental pollutants consisting of a minimum of two fused aromatics rings originating from the incomplete combustion of organic matter and/or anthropogenic sources. Numerous possible anthropogenic and natural sources make the presence of PAH ubiquitous in the environment. The carcinogenic nature of some PAH and their ubiquitous presence makes their chemical analysis a topic of environmental and toxicological importance. Although...
Show morePolycyclic aromatic hydrocarbons (PAH) are a class of environmental pollutants consisting of a minimum of two fused aromatics rings originating from the incomplete combustion of organic matter and/or anthropogenic sources. Numerous possible anthropogenic and natural sources make the presence of PAH ubiquitous in the environment. The carcinogenic nature of some PAH and their ubiquitous presence makes their chemical analysis a topic of environmental and toxicological importance. Although environmental monitoring of PAH is an important step to prevent exposure to contaminated sites, it provides little information on the actual uptake and subsequent risks. Parent PAH are relatively inert and need metabolic activation to express their carcinogenicity. Covalent binding to DNA appears to be the first critical step in the initiation of the tumor formation process.To this end, the determination of short term biomarkers (-) such as monohydroxy-PAH metabolites (OH-PAH) - fills an important niche to interpret actual PAH exposure levels, prevent extreme body burdens and minimize cancer risk. One would certainly prefer an early warning parameter over a toxicological endpoint (-) such as DNA-adducts (-) indicating that extensive damage has already been done. Several methods have been developed to determine OH-PAH in specific tissue or excreta and food samples. The general trend for the analysis of OH-PAH follows the pattern of sample collection, sample clean-up and pre-concentration, chromatographic separation and quantification. Popular approaches for sample clean-up and pre-concentration include liquid-liquid extraction (LLE) and solid-phase extraction (SPE). Chromatographic separation and quantification has been based on high-performance liquid chromatography-room temperature fluorescence detection (HPLC) and gas chromatography-mass spectrometry (GC-MS).Although chromatographic techniques provide reliable results in the analysis of OH-PAH, their experimental procedures are time consuming and expensive. Elution times of 30-60 minutes are typical and standards must be run periodically to verify retention times. 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. On the other end of the concentration range, many samples are (")zeroes,(") i.e. the concentrations are below detection limits. Additional problems arise when laboratory procedures are scaled up to handle thousands of samples under mass screening conditions. Under the prospective of a sustainable environment, the large usage of organic solvents is one of the main limitations of the current chromatographic methodology.This dissertation focuses on the development of a screening methodology for the analysis of OH-PAH in urine and milk samples. Screening techniques capable of providing a (")yes or no(") answer to OH-PAH contamination prevent unnecessary scrutiny of un-contaminated samples via conventional methods, reduce analysis cost and expedite the turnaround time for decision making purposes. The proposed methodology is based on capillary zone electrophoresis (CZE) and synchronous fluorescence spectroscopy (SFS). Metabolites extraction and pre-concentration is achieved with optimized SPE, LLE and/or QuEChERS (quick, easy, cheap, effective, rugged and safe) procedures. The small sample and extracting solvent volumes facilitate the simultaneous extraction of numerous samples via an environmentally friendly procedure, which is well-suited for routine monitoring of numerous samples. Sample stacking is successfully implemented to improve CZE limits of detection by two orders of magnitude. The unique electrophoretic pattern of positional isomers of OH-PAH demonstrates the potential of CZE for the unambiguous determination of metabolites with similar chromatographic behaviors and virtually similar fragmentation patterns. The direct determination of OH-PAH without chromatographic separation is demonstrated via SFS. The non-destructive nature of SFS provides ample opportunity for further metabolite confirmation via chromatographic techniques.
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Date Issued
2013
Identifier
CFE0005102, ucf:50761
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005102
Synthetic Design and Characterization of Polycyclic Aromatic Compounds in Molecular and Extended System
Title
Synthetic Design and Characterization of Polycyclic Aromatic Compounds in Molecular and Extended System.
Creator
Pour, Gavin, Belfield, Kevin, Frazer, Andrew, Elsheimer, Seth, University of Central Florida
Abstract / Description
The work presented herein focuses on the synthesis and characterization of polycyclic aromatic compounds for a wide variety of toxicological, analytical, and electronic applications. First, the modular synthesis of 12 dibenzo- and naphtho- fluoranthene polycyclic aromatic hydrocarbons (PAHs) via a Pd-catalyzed five-membered ring closing procedure is discussed. By understanding the various modes through which the Pd migrates during transformation, structural rearrangements were bypassed,...
Show moreThe work presented herein focuses on the synthesis and characterization of polycyclic aromatic compounds for a wide variety of toxicological, analytical, and electronic applications. First, the modular synthesis of 12 dibenzo- and naphtho- fluoranthene polycyclic aromatic hydrocarbons (PAHs) via a Pd-catalyzed five-membered ring closing procedure is discussed. By understanding the various modes through which the Pd migrates during transformation, structural rearrangements were bypassed, obtaining regioselectivity through various redesigns in the synthetic route. Each compound in the serious was rigorously characterized via 1D/2D NMR, absorption and emission spectroscopy as well as cyclic voltammetry, which shows vast differences due to small structural changes between these constitutional isomers. Next, a series of polyphenylated organic ligands for zirconium metal organic frameworks is presented as materials for post-synthetic Scholl cyclodehydrogenation. Lastly, a series of organic linkers featuring covalently anchored redox-active pendants is explored for tuneable redox activity in Zr-based metal-organic frameworks. Thin-films were grown onto fluorine-doped tin-oxide glass electrodes and analyzed by cyclic voltammetry. This is the first reported pre-synthetic incorporation of covalently-bound ferrocenyl pendants into such a system. By attenuating the proportions of redox active and inactive links the oxidative peak currents could be tuned. This body of work represents a contribution toward the practical design and synthesis of polycyclic aromatic for a wide variety of analytical and electrochemical applications.
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Date Issued
2019
Identifier
CFE0007512, ucf:52647
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007512
Novel Developments on the Extraction and Analysis of Polycyclic Aromatic Hydrocarbons in Environmental Samples
Title
Novel Developments on the Extraction and Analysis of Polycyclic Aromatic Hydrocarbons in Environmental Samples.
Creator
Wilson, Walter, Campiglia, Andres, Belfield, Kevin, Rex, Matthew, Harper, James, Hoffman, Jay, University of Central Florida
Abstract / Description
This dissertation focuses on the development of analytical methodology for the analysis of polycyclic aromatic hydrocarbons (PAHs) in water samples. Chemical analysis of PAHs is of great environmental and toxicological importance. Many of them are highly suspect as etiological agents in human cancer. Among the hundreds of PAHs present in the environment, the U.S. Environmental Protection Agency (EPA) lists sixteen as "Consent Decree" priority pollutants. Their routine monitoring in...
Show moreThis dissertation focuses on the development of analytical methodology for the analysis of polycyclic aromatic hydrocarbons (PAHs) in water samples. Chemical analysis of PAHs is of great environmental and toxicological importance. Many of them are highly suspect as etiological agents in human cancer. Among the hundreds of PAHs present in the environment, the U.S. Environmental Protection Agency (EPA) lists sixteen as "Consent Decree" priority pollutants. Their routine monitoring in environmental samples is recommended to prevent human contamination risks.A primary route of human exposure to PAHs is the ingestion of contaminated water. The rather low PAH concentrations in water samples make the analysis of the sixteen priority pollutants particularly challenging. Current EPA methodology follows the classical pattern of sample extraction and chromatographic analysis. The method of choice for PAHs extraction and pre-concentration is solid-phase extraction (SPE). PAHs determination is carried out via high-performance liquid chromatography (HPLC) or gas chromatography/mass spectrometry (GC/MS). When HPLC is applied to highly complex samples, EPA recommends the use of GC/MS to verify compound identification and to check peak-purity of HPLC fractions. Although EPA methodology provides reliable data, the routine monitoring of numerous samples via fast, cost effective and environmentally friendly methods remains an analytical challenge. Typically, 1 L of water is processed through the SPE device in approximately 1 h. The rather large water volume and long sample processing time are recommended to reach detectable concentrations and quantitative removal of PAHs from water samples. Chromatographic elution times of 30 (-) 60 min are typical and standards must be run periodically to verify retention times. If concentrations of targeted PAHs are found to lie outside the detector's response range, the sample must be diluted (or concentrated), and the process repeated. In order to prevent environmental risks and human contamination, the routine monitoring of the sixteen EPA-PAHs is not sufficient anymore. Recent toxicological studies attribute a significant portion of the biological activity of PAH contaminated samples to the presence of high molecular weight (HMW) PAHs, i.e. PAHs with MW ? 300. Because the carcinogenic properties of HMW-PAHs 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. Unfortunately, established methodology cannot always meet the challenge of specifically analyzing HMW-PAHs at the low concentration levels of environmental samples. The main problems that confront classic methodology arise from the relatively low concentration levels and the large number of structural isomers with very similar elution times and similar, possibly even virtually identical, fragmentation patterns. This dissertation summarizes significant improvements on various fronts. Its first original component deals with the unambiguous determination of four HMW-PAHs via laser-excited time-resolved Shpol'skii spectroscopy (LETRSS) without previous chromatographic separation. The second original component is the improvement of a relatively new PAH extraction method - solid-phase nanoextraction (SPNE) - which uses gold nanoparticles as extracting material for PAHs. The advantages of the improved SPNE procedure are demonstrated for the analysis of EPA-PAHs and HMW-PAHs in water samples via GC/MS and LETRSS, respectively.
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Date Issued
2014
Identifier
CFE0005443, ucf:50384
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005443
Improvements on Instrumentation to Explore the Multidimensionality of Luminescence Spectroscopy
Title
Improvements on Instrumentation to Explore the Multidimensionality of Luminescence Spectroscopy.
Creator
Moore, Anthony, Campiglia, Andres, Chumbimuni Torres, Karin, Harper, James, Rex, Matthew, Lee, Woo Hyoung, University of Central Florida
Abstract / Description
This dissertation presents experimental and instrumentation developments that take full advantage of the multidimensional nature of line narrowing spectroscopy at liquid nitrogen (77 K) and liquid helium (4.2 K) temperatures. The inconvenience of sample freezing procedures is eliminated with the aid of cryogenic fiber optic probes. Rapid collection of multidimensional data formats such as wavelength time matrices, excitation emission matrices, time-resolved excitation emission matrices and...
Show moreThis dissertation presents experimental and instrumentation developments that take full advantage of the multidimensional nature of line narrowing spectroscopy at liquid nitrogen (77 K) and liquid helium (4.2 K) temperatures. The inconvenience of sample freezing procedures is eliminated with the aid of cryogenic fiber optic probes. Rapid collection of multidimensional data formats such as wavelength time matrices, excitation emission matrices, time-resolved excitation emission matrices and time resolved excitation emission cubes is made possible with the combination of a pulsed tunable dye laser, a spectrograph and an intensifier-charged coupled device. These data formats provide unique opportunities for processing vibrational luminescence data with second order multivariate calibration algorithms. The use of cryogenic fiber optic probes is extended to commercial instrumentation. An attractive feature of spectrofluorimeters with excitation and emission monochromators is the possibility to record synchronous spectra. The advantages of this approach, which include narrowing of spectral bandwidth and simplification of emission spectra, were demonstrated with the direct analysis of highly toxic dibenzopyrene isomers. The same is true for the collection of steady-state fluorescence excitation-emission matrices. These approaches provide a general solution to unpredictable spectral interference, a ubiquitous problem for the analysis of organic pollutants in environmental samples of unknown composition. Since commercial spectrofluorimeters are readily available in most academic institutions, industrial settings and research institutes, the developments presented here should facilitate the widespread application of line-narrowing spectroscopic techniques to the direct determination, no chromatographic separation, of highly toxic compounds in complex environmental matrixes of unknown composition.
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Date Issued
2015
Identifier
CFE0005847, ucf:50934
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005847
Analysis of Benzopyrenes and Benzopyrene Metabolites by Fluorescence Spectroscopy Techniques
Title
Analysis of Benzopyrenes and Benzopyrene Metabolites by Fluorescence Spectroscopy Techniques.
Creator
Al-Farhani, Bassam, Campiglia, Andres, Harper, James, Zou, Shengli, Frazer, Andrew, Lee, Woo Hyoung, University of Central Florida
Abstract / Description
Polycyclic aromatic hydrocarbons (PAHs) are some of the most common and toxic pollutants encountered worldwide. Presently, monitoring is restricted to sixteen PAHs, but it is well understood that this list omits many toxic PAHs. Among the (")forgotten(") PAHs, isomers with molecular weight 302 are of particular concern due to their high toxicological properties. The chromatographic analysis of PAHs with MW 302 is challenged by similar retention times and virtually identical mass fragmentation...
Show morePolycyclic aromatic hydrocarbons (PAHs) are some of the most common and toxic pollutants encountered worldwide. Presently, monitoring is restricted to sixteen PAHs, but it is well understood that this list omits many toxic PAHs. Among the (")forgotten(") PAHs, isomers with molecular weight 302 are of particular concern due to their high toxicological properties. The chromatographic analysis of PAHs with MW 302 is challenged by similar retention times and virtually identical mass fragmentation patterns.The first original component of this dissertation evolves from a high-resolution spectroscopic approach specifically developed to fulfil this gap. Herein, 4.2 K Laser-Excited Time-Resolved Shpol'skii Spectroscopy (4.2K LETRSS) is applied to the analysis of HMW-PAHs in a complex coal tar standard reference material (SRM 1597a). The spectral and lifetime information obtained with LETRSS provide the required selectivity for the unambiguous determination of PAH isomers in the high-performance liquid chromatography (HPLC) fractions. Complete LETRSS analysis is possible with microliters of HPLC fractions and organic solvent. The excellent analytical figures of merit associated to its non-destructive nature, which provides ample opportunity for further analysis with other instrumental methods, makes this approach a unique alternative for the analysis of isomers of HMW-PAHs in complex environmental samples.The second original component of this dissertation focuses on the development of screening methodology for the routine analysis of PAH metabolites in urine samples. It explores the room-temperature fluorescence (RTF) properties of 3-hydroxy-benzo[a]pyrene, benzo[a]pyrene-trans-9,10-dihydrodiol, benzo[a]pyrene-r-7,t-8,c-9-tetrahydrotriol and benzo[a]pyrene-r-7,t-8,c-9,c-10-tetrahydrotetrol previously extracted with octadecyl-silica membranes. RTF measurements from extraction membranes are carried out with the aid of fiber optic probe that eliminates the need for manual optimization of signal intensities. Relative standard deviations varying from 2.07% (benzo[a]pyrene-r-7,t-8,c-9-tetrahydrotriol) to 8.55% (3-hydroxy-benzo[a]pyrene) were obtained with a straightforward procedure. Analytical recoveries from human urine samples varied from 87.54 (&)#177; 3.11% (3-hydroxy-benzo[a]pyrene) to 99.77 (&)#177; 2.48% (benzo[a]pyrene-r-7,t-8,c-9,c-10-tetrahydrotetrol). The excellent analytical figures of merit and the simplicity of the experimental procedure demonstrate the potential of Solid phase extraction-RTF for screening biomarkers of PAH exposure in numerous urine samples.
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Date Issued
2016
Identifier
CFE0006520, ucf:51363
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006520
Measuring and Modeling NMR and Emission Spectra to Gain New Insight into Challenging Organic Compounds
Title
Measuring and Modeling NMR and Emission Spectra to Gain New Insight into Challenging Organic Compounds.
Creator
Powell, Jacob, Harper, James, Campiglia, Andres, Beazley, Melanie, Richardson, David, Blair, Richard, University of Central Florida
Abstract / Description
The advancement of theoretical methods in recent years has allowed the calculation of highly accurate spectroscopic parameters. Comparing these values to the corresponding experimental data can allow molecular structures to be elucidated. This dissertation details the use of experimental and theoretical data from nuclear magnetic resonance (NMR) and fluorescence spectroscopy to determine structure. Herein the NMR focus is on measuring (&) modeling chemical shift anisotropy and one-bond carbon...
Show moreThe advancement of theoretical methods in recent years has allowed the calculation of highly accurate spectroscopic parameters. Comparing these values to the corresponding experimental data can allow molecular structures to be elucidated. This dissertation details the use of experimental and theoretical data from nuclear magnetic resonance (NMR) and fluorescence spectroscopy to determine structure. Herein the NMR focus is on measuring (&) modeling chemical shift anisotropy and one-bond carbon-carbon J-coupling constants (1JCC). The fluorescence analysis models vibrationally resolved fluorescence spectra.Chemical shift anisotropy techniques were used to study two conflicting crystal structures of the n-alkyl fatty acid, lauric acid. These two crystal structures differ only in their COOH conformation. Lattice-including density functional theory (DFT) refinements of each crystal structure failed to match experimental data leading to the proposal of a third crystal structure with a hydrogen disordered COOH moiety. This disorder strengthens the hydrogen bond providing a new rationalization to the long observed non-monotonic melting behavior of fatty acids having even and odd numbers of carbons.The INADEQUATE is a NMR experiment that directly establishes the skeleton of organic compounds by measuring the 1JCC throughout a molecule. The low occurrence of 13C-13C pairs (1 in 10,000) and breaks in connectivity due to the presence of heteroatoms causes challenges to INADEQUATE analysis. Here, the insensitivity problem is overcome using analysis software that automatically processes data and identifies signals, even when they are comparable in magnitude to noise. When combined with DFT 1JCC predictions,configuration and confirmations of the natural products 5-methylmellein and hydroheptelidic acid are elucidated.Vibrationally resolved fluorescence spectra of high molecular weight PAHs can be accurately calculated through time-dependent density functional theory (TD-DFT) methods. Here, the theoretical spectral profiles of certain PAHs are shown to match experimental high- resolution fluorescence spectra acquired at cryogenic temperatures. However, in all cases, theoretical spectra were systematically offset from experimental spectra. To decrease these uncertainties spectra were empirically corrected and an automated scheme employed to match theoretical spectra with all possible experimental spectra. In all cases the theoretical spectra were correctly matched to the experimental spectra.
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Date Issued
2017
Identifier
CFE0006953, ucf:51680
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006953