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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

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

Huiyong, Wang 01 January 2010 (has links)
Polycyclic aromatic hydrocarbons (PAH) are important environmental pollutants originating from a wide variety of natural and anthropogenic sources. Because many of them are highly suspect as etiological agents in human cancer, chemical analysis of PAH is of great environmental and toxicological importance. Current methodology for PAH follows the classical pattern of sample preparation and chromatographic analysis. Sample preparation preconcentrates PAH, simplifies matrix composition, and facilitates analytical resolution in the chromatographic column. Among the several approaches that exist to pre-concentrate PAH from water samples, the Environmental Protection Agency (EPA) recommends the use of solid-phase extraction (SPE). High-performance liquid chromatography (HPLC) and gas chromatographymass 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 iv 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 TimeResolved 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 v 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.6
182

Chemical analysis of polycyclic aromatic compounds in plastic materials used in indoor environments

Yara, Lania January 2023 (has links)
Human bodies are in constant interaction with materials containing known and unknown chemicals of hazardous behavior. One group of chemicals are polycyclic aromatic compounds (PACs) which can be present in both indoor and outdoor materials, commonly in plastics. PACs are known for their cancerogenic behavior and thus should be considered and studied in an attempt to decrease human exposure. The following project reports the execution and results from chemical analysis of 48 PACs including parent polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs and dibenzothiophenes (S-PAC), searched for in different materials commonly found indoors. Eleven samples were prepared and analyzed using GC/MS target analysis. 23 out of the 33 parent PAHs targeted were detected and quantified. In addition, 12 out of 15 alkylated PAHs including four dibenzothiophenes (S-PAC) were detectable in the samples. The contents of parent PAHs ranged from 105 ng/g to 6700 ng/g in the samples, with the highest value being present in a laminated artificial leather sample. The alkylated PAHs ranged from 34 ng/g to 3000 ng/g, and a recycled hard plastic contained the highest amount. Amongst the parent PAHs, the dominating compound in the samples was phenanthrene. For the alkylated PAHs, 2-methylnaphtalene was the compound present in the highest mass fraction. When comparing the samples, most similarities in PAC composition could be seen in the artificial leather samples excluding a high content of naphthalene in the laminated leather. The recycled plastic material consisted of the highest variety of PACs. The results presented that none of the samples exceeded the limit values set by EU regulation regarding eight PAHs (PAH8) in consumer products. However, poor recovery in addition to poor resolution of the majority of the high molecular mass compounds suggest further investigation of method optimization.
183

THE INTERACTION OF CHEMICAL AND NATURAL STRESSORS ON CARDIOVASCULAR DYNAMICS OF TELEOST FISH

Cypher, Alysha D. January 2017 (has links)
No description available.
184

STEAM EXTRACTION OF POLYCYCLIC AROMATIC HYDROCARBONS AND LEAD FROM CONTAMINATED SEDIMENT USING SURFACTANT, SALT AND AKALINE CONDITIONS

WEINKAM, GRANT 03 July 2007 (has links)
No description available.
185

Firefighters’ Exposure to Fine Particles and Polycyclic Aromatic Hydrocarbons

Hoffman, Joseph D. 19 October 2010 (has links)
No description available.
186

Effects of Cyclodextrin on Extraction and Fungal Remediation of Polycyclic Aromatic Hydrocarbon-contaminated Mahoning River Sediment

Pabba, Sowmya 02 September 2008 (has links)
No description available.
187

Time-Dependent Density-Functional Description of the <sup>1</sup>L<sub>a</sub> State in Polycyclic Aromatic Hydrocarbons

Richard, Ryan M. 20 July 2011 (has links)
No description available.
188

Photoluminescence by Interstellar Dust

Vijh, Uma Parvathy 05 October 2005 (has links)
No description available.
189

The synthesis of some new aromatic polycyclic hydrocarbons

Ojakaar, Leo January 1964 (has links)
In 1933, benzo[a]pyrene, a hydrocarbon, which was and still is of very great importance for cancer research, was isolated from coal tar and also was synthesized. In recent years more than 450 synthetic compounds have been found to be carcinogenic, and more than 200 are polycyclic aromatic hydrocarbons, their derivatives and analogues. Recently a new polynuclear hydrocarbon, a seven ring compound naphtho[2,1-a]perylene was synthesized in This Laboratory Physiological tests have revealed this compound to be a potent carcinogen. This experience has prompted a new initiative to prepare a number of related compounds of this type in order to bring further insight to the relation between chemical structure and the mechanism of physiological activity. During the synthesis of the four new seven fused aromatic ring systems and a new eight fused aromatic ring system, several modifications and improvement of existing synthetic procedures were made. A recently published modification of the Rosenmund-von Braun method of nitrile synthesis was successfully applied to the preparation of 2-(2-naphthylmethyl)benzonitrile. It was found that 2-(2-naphthylmethyl)phenyl-1-naphthyl ketone and 2-(2-naphthylmethyl)phenyl-2-naphthyl ketone could be prepared by the reaction of a Grignard reagent with a nitrile as well as by the inverse addition of a Grignard reagent to the appropriate acid chlorides. The alumina cyclodehydrogenation procedure was confirmed to be the, only method of synthesis that yields 12-(1-naphthyl)-benz[a]anthracene from its precursor ketone. The yield of 12-(2-naphthyl)benz[a]anthracene was increased from 61% to 83% when anhydrous hydrogen fluoride was used in place of 48% hydrogen bromide and glacial acidic acid as the cyclodehydration media of the precursor ketone. A new cyclodehydrogenation procedure was developed. This procedure, which employs a mixture of aluminum chloride-stannic chloride and alumina, was used to prepare a new hydrocarbon, naphtho[l,2-a]-perylene. An aluminum chloride-sodium chloride melt permeated with carbon dioxide was successfully employed in the preparation of naphtho[2,2-1]benzo- (a]pyrene, naphtho(l,2-l]benzo[a]pyrene, and naphtho- (2,3-1]benzo[a]pyrene. It was shown that high temperature gas chromatography with ionization detectors can be used with success to analyze all of the above discussed ketones, benz[a]anthracenes as well as the new perylene and pyrenes. Additional support of the validity of the. structures of naphtho[1,2-a]perylene and naphtho- [2,1-1]benzo[a]pyrene was provided when the cyclodehydrogenation of these hydrocarbons yielded one and the same product, naphtho[l,7,8-efg]anthanthrene. It was observed that the correlation between color and structure of the newly prepared hydrocarbons follows the principles of annelation. When the ultraviolet and visible spectra peak frequencies were compared it was found that the values and positions of the peaks follow the principles of the annelation method. The examination of the infrared absorption spectra revealed that naphtho[l,2-a]perylene, naphtho[2,1l-1]benzo[a]pyrene, naphtho[1,2-1]benzo[a]-pyrene, and naphtho[2,3-1]benzo[a]pyrene exhibited Peaks at all four, "solo," "duo," "trio," and "quartet", carbon-hydrogen vibration regions, but as expected naphtho[1,7,8-efg]anthanthrene had the "quartet" carbon-hydrogen peak missing between 770 and 755 cm. which further substantiated the validity of the naphtho[1,7,8-efg]anthanthrene structure. The TNF molecular adducts of the five newly prepared compounds, naphtho[1,2-a]perylene, naphtho- [2,1-1]benzo[a]pyrene, naphtho1l,2-1]benzo[a]pyrene, naphtho[2,3-1]benzo[a]pyrene, and naphtho[1,7,8-efg]-anthanthrene were prepared and their melting points recorded. In order to ascertain the structures of the naphtho[1,2-a]perylene and the naphtho[1,2-l]benzo[a]-pyrene obtained from the cyclodehydrogenation of 12-(1-naphthyl)benz[a]anthracene and 12-(2-naphthyl)-benz[a]anthracene, respectively, other routes of synthesis were undertaken. The hydrocarbon, 11-(1-naphthyl)benz[a]anthracene, was prepared by the reaction of 1-naphthylmagnesium bromide with 11-keto-5,6,8,9,10,11-hexahydrobenz[a]- anthracene which on distillation under reduced pressure gave 11-(1-naphthyl)-5,6,8,9-tetrahydrobenz[a]anthracene and on aromatization yielded 11-(1-naphthyl)benz[a]-anthracene. When 1-naphthyl magnesium bromide was allowed to react with the 11-keto-8,9,10,11-tetrahydrobenz[a]anthracene, 11-(1-naphthyl)-8,9~dihydrobenz[a]anthracene was obtained when distilled under reduced pressure. This, likewise, gave 11-(1-naphthyl)- benz[a]anthracene on aromatization. Naphtho[1,2-a]perylene was synthesized unequivocally from 11-(1-naphthyl)benz[a]anthracene via a cyclodehydrogenation reaction. The hydrocarbon, 1-(1-naphthyl)-1,2,3,4-tetrahydrobenz[a]anthracene, was prepared by the reaction of 1-naphthylmagnesium bromide with 1-keto-1,2,3,4- tetrahydrobenz[a]anthracene. On distillation under reduced pressure 1-(1-naphthyl)-1,2,3,4-tetrahydrobenz[a]anthracene was obtained. Under the conditions of an aromatization procedure, naphtho[1,2-1]benzo[a]-pyrene was obtained. The hydrocarbons 11-(1l-naphthyl)-5,6,8,9-tetrahydrobenz[a]anthracene, 11-(1-naphthyl)-8,9-dihydrobenz[a]anthracene, 11-(1-naphthyl)benz[a]-anthracene, 1-(1-naphthyl)-1,2,3,4-tetrahydrobenz[a]anthracene are additional new compounds. / Ph. D.
190

The synthesis and reactions of 2-(1-Naphthylmethyl)-2'- Carboxybenzophenone

Greenwood, Edward James 09 November 2012 (has links)
The structures of the six new compounds and the TNF molecular complex were substantiated by satisfactory elemental analyser. The infrared and ultraviolet absorption spectra of the six new compounds were recorded. / Master of Science

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