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Evaluation Of Solid Phase Extraction Followed By Supercritical Fluid Elution Of Semi-Volatile Organic Compounds In Toxicity Characteristic Leachates, William Edward Corl Iii

Chemistry & Biochemistry Theses & Dissertations

The Environmental Protection Agency (EPA) developed the toxicity characteristic leaching procedure (TCLP) to determine the potential for unknown wastes to leach haz.ardous constituents into the environment. Methods currently being used for the extraction of semi-volatile organic compounds from aqueous TCLP leachates involve acid/base partitioning into methylene chloride. The concentrated extract is then analyzed by gas chromatography/mass spectrometry (GC/MS). The methods are either timeconsuming or labor intensive and they generate significant volumes of haz.ardous wastes themselves. Considering the haz.ards and disposal costs of methylene chloride wastes, great interest has been elicited by the EPA in other extraction techniques which would reduce …

Fabrication And Evaluation Of Boron-Doped Cvd Diamond Microelectrodes, Song Pang

Chemistry & Biochemistry Theses & Dissertations

The electrochemical behavior of boron-doped diamond microelectrodes has been studied in acetonitrile solutions containing two redox couples using cyclic voltammetry. One test system is 1-2.5 mM ferrocene, containing 0.1 M Tetrabutyl ammonium hexafluorophosphate (TBAH). This well-known reversible redox system involves only one electron transfer with little or no change in the solvation sphere and no breakage/formation of chemical bonds. Another test system is a 1 mM S₂Mo₁₈0₆₄^4- solution containing 0.1 M HCIO₄. This is one of the most complicated redox systems. In the presence of acid, electrons are usually transferred consecutively and …

Comparison Of The Dichlorination Of Organic N-Chloramines By Caroate And By Bisulfite: A Kinetic Study, Said H. Lubbad

Chemistry & Biochemistry Theses & Dissertations

Bisulfite is commonly used to dechlorinate chlorinated municipal wastewater. However, several studies suggest that bisulfite is not effective in dechlorinating N-chlorinated amino components of wastewater. The purpose of this study was to investigate the effectiveness of an alternate dechlorinating agent, caroate (peroxysulfate), and to compare its rate of dechlorination of three different types of chloramines with that of bisulfite.

Four N-chlorinated amino compounds were investigated: N-chlorodiethylamine, N­ chloroalanylphenylalanine, N-chloroglycylphenylalanine, and N-[2-(N'-chloroimino)­ propanoyl]phenylalanine. These compounds were selected from different families of N­ chloramines to study the effect of structure on dechlorination by both caroate and bisulfite. At pH …

Speciation Of Selenium In Serum, Alice Tsapayi-Musapatike

Chemistry & Biochemistry Theses & Dissertations

We investigated the separation of selenoprotein P and extracellular (serum) glutathione peroxidase using a concanavalin A affinity column. We were able to show that the method does not adequately separate serum glutathione peroxidase from selenoprotein P because human glutathione peroxidase binds strongly to the column. We also found that albumin can interfere with measurement serum of glutathione peroxidase activity when hydrogen peroxide is used as the substrate. When t-butyl hydroperoxide was used as the substrate, less than 10% of the measured activity was due to the presence of albumin. We also found that the pH of the elution buffer plays …

Development Of A Fluorescent Indicator For Inorganic Monochloramine, Xiaojun Dong Zou

Chemistry & Biochemistry Theses & Dissertations

Current methods used to determine combined residual chlorine cannot distinguish between inorganic monochloramine (NH₂Cl) and organic chloramines. Studies described in this thesis were carried out to develop a novel method of determining the concentration of inorganic monochloramine in aqueous solutions. Based on the observation that the reaction of 3-formyl-1-methylpyridinium chloride (3FMPCl) with NH₂Cl produces a solution which is fluorescent, experiments were conducted to characterize the reaction and optimize the experimental conditions. Using the finalized protocol, NH₂Cl measurements were made in the presence and absence of organic amines and compared with a commonly used N, …

Development Of Solid Phase Microextraction Methods For Contraband Drugs, Vangielynn Cruz Tersol

Chemistry & Biochemistry Theses & Dissertations

The objective of this study is to develop analytical methods for studying contraband drugs at nanogram levels and to demonstrate the utility of the methods. A method which combines solid phase microextraction with ion mobility spectrometry (SPME-IMS) was developed. The SPME-IMS method was used as a rapid screening tool in studying the chemistry of cocaine HCI, heroin HCI, and heroin freebase on surfaces. The total time for sample preparation, reaction, and analysis is approximately seven minutes. Another method that was developed is one that combines solid phase microextraction with gas chromatography (SPME-GC) for the quantitative analysis of cocaine freebase and …