Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains viii, 59 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 54-56).

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed Oct. 10, 2007). PDF text: 234 p. : ill. (some col.) UMI publication number: AAT 3259631. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis (M.S.)--Texas State University-San Marcos, 2007. / Vita. Includes bibliographical references (leaves 80-85).

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Dissertation presented in partial compliance with the requirements for the Masters Degree in Technology: Chemistry, Durban University of Technology, 2009. / This study was mainly a response to a challenge faced by ESKOM in its coal-fired power stations. In spite of using high purity water to drive the turbines, the latter were damaged by ‘pitting’, possibly related to acids generated at high temperatures. In the light of this a relatively simple method for determination of short chain organic acids was identified by comparing the efficacies of several methods. It was found that high performance liquid chromatography (HPLC) method preceded by derivatization (with o-nitrophenyl hydrazine) is suitable for analyzing mixtures of simple acids at ppb levels. Calibration was effected by using methanoic acid (formic acid), ethanoic acid (acetic acid), propanoic acid (propionic acid) and butanoic acid (butyric acid). The HPLC instrument used was from Thermo Separations with P2000 pump, SN 4000 interface and UV1000 with a column heater. A comparative study between the HPLC methods using ion exclusion and partition chromatography was carried out in order to find a suitable method that can be used with aqueous environmental samples. The two essential columns that were used were ion exclusion Phenomenex Rezex OA column and a Nucleodur C8 column. The method of partition chromatography using a C8 column showed the most success using a mobile phase consisted of acidified water using HCl (pH4.5) along with a 60:40 Acetonitrile/Methanol mixture. Both isocratic and gradient programs were utilized. Limits of detection were improved from 800ppb (formic acid), 480ppb (acetic), 350ppb (propionic) and 680ppb (butyric acid) to 25ppb (acetic), 60ppb (propionic) and 90ppb (butyric). Samples used in analysis were collected from the main stream, economiser, condensers, polishing plant and turbines of the Tutuka Power Station in Mpumalanga province and analysed using with final developed method / Eskom Tertiary Support Programme. Durban University of Technology

abstract: A new analytical method is proposed for measuring the deuterium to hydrogen ratio (D/H) of non-stoichiometric water in hydrous minerals via pyrolysis facilitated gas-chromatography - isotope ratio mass spectrometry (GC-IRMS). Previously published analytical methods have reported a poorly understood nonlinear dependence of D/H on sample size, for which any accurate correction is difficult. This sample size effect been variously attributed to kinetic isotope fractionation within the mass spectrometer and peripheral instruments, ion source linearity issues, and an unstable H_3^+-factor or incorrect H_3^+-factor calculations. The cause of the sample size effect is here identified by examinations of individual chromatograms as well as bulk data from chromatographic peaks. It is here determined that it is primarily an artifact of the calculations employed by the manufacturer's computer program, used to both monitor the functions of the mass spectrometer and to collect data. Ancillary causes of the sample size effect include a combination of persistent background interferences and chromatographic separation of the isotopologues of molecular hydrogen. Previously published methods are evaluated in light of these findings. A new method of H_3^+-factor and D/H calculation is proposed which makes portions of the Isodat software as well as other published calculation methods unnecessary. Using this new method, D/H is measured in non-stoichiometric water in chert from the Cretaceous Edwards Group, Texas, as well as the Precambrian Kromberg Formation, South Africa, to assess hydrological conditions as well as to estimate the maximum average surface temperature during precipitation of the chert. Data from Cretaceous chert are consistent with previously published data and interpretations, based upon conventional analyses of large samples. Data from Precambrian chert are consistent with maximum average surface temperatures approaching 65°C during the Archean, instead of the much lower temperatures derived from erroneous methods of sample preparation and analysis. D/H is likewise measured in non-stoichiometric water in silicified basalt from the Precambrian Hooggenoeg Complex, South Africa. Data are shown to be consistent with D/H of the Archean ocean similar to present day values. / Dissertation/Thesis / M.S. Geological Sciences 2011

Being able to detect if drugs were used in the commission of a crime, and if so what drugs, is of great importance. For many cases these tests can be carried out on an intimate blood or urine sample (one recovered directly from the subject in question), however this may not always be the case. In cases where a dried bloodstain is the only source of biological material, identifying the presence of drugs affecting an individual at the time of stain deposition has not been well studied. Towards this goal, two methods of detection of drugs of abuse in dried bloodstains were evaluated: lateral flow immunoassay test cards and gas chromatography-mass spectrometry. Stains were created using certified drug-free blood spiked with analytes of interest, and were then extracted and introduced into each testing method. Both methods proved effective for the detection of one or two of the five chosen analytes (amphetamine, cocaine, morphine 3-ß-D-glucuronide, phencyclidine and 11-nor-Δ9-tetrahydracannabinol), even after 24 hours of drying at room temperature. With further method optimization and more thorough method development, these methods may, in the future, be effectively used for drug detection in forensic stains. However, neither method evaluated in this study was able to detect all of the drugs tested.

Synthetic drugs such as piperazines are among the most commonly abused drugs and are typically consumed by younger populations. Because of their popularity, developing optimized analytical strategies designed to improve detection and interpretation of synthetic piperazines is of interest to the forensic community. To improve the likelihood that a substance of interest is detected, careful evaluation into the mass spectrometry signal is required. However, with all analytical pursuits, there is a limit at which the substance cannot be detected with certainty; thus a threshold is commonly referred to as the limit of detection (LOD). Formally, the LOD is the minimum amount of analyte (concentration, mass, number of molecules, etc.) that can be detected at a known confidence level. The purpose of this research was to use common analytical methods to calculate the LOD and verify the results with previous work at the Boston University forensic toxicology laboratory. Data from the Liquid Chromatography-tandem Mass Spectrometer (LC-MS/MS) was previously generated and consisted of signal intensity information in the form of peak height and peak area, from titrations of eight synthetic piperazines that included: Benzylpiperazine (BZP), 1-(3-chlorophenyl)-piperazine (mCPP), 3-trifluoromethylphenylpiperazine monohydrochloride (TFMPP), methylbenzylpiperazine (MBZP), 1-(4-fluorobenzyl)-piperazine (FBZP), 2,3-dichlorophenylpiperazine (DCPP), para-fluorophenylpiperazine (pFPP) and para-methoxyphenylpiperazine (MeOPP). Generally, the LOD is determined by first evaluating the signal in the absence of analyte and determining the probability that signal, , crosses the signal threshold, . The signal threshold is based upon the false detection rate the laboratory can withstand for a given interpretation scheme. In instances where very small levels of false detections can be tolerated, a large is chosen. In other circumstances, where noise detection can adequately be interpreted, a low is chosen. In chromatography and radiography the typical one sided =0.003. The number of molecules for each analyte at each concentration (20 ng/mL, 50 ng/mL, 200 ng/mL, 500 ng/mL, 1000 ng/mL and 2000 ng/mL) was determined and used throughout this work. Peak area signals and ratios versus number of molecules for each analyte were used to, first, visually inspect the linearity of signal to analyte level. It was determined that using internal standards improved linearity, as expected; however, the data suggested that absolute signal intensity was sufficient to compute the LOD for these compounds. Generally accepted methods of calculating LOD were not used for this research as the signal from the blank was not detected most likely due to the sensitivity of the instrument used. This study used an extrapolation of the data and propagation of errors method to calculate the LOD as the signal from the blank was not needed. For all eight analytes, the LOD calculated was similar to the lowest concentration (20 ng/mL) used when validating this method. This research needs to be expanded on to include more concentration points and see the plateau effect at higher concentrations. This will provide information to analytical chemists when a blank signal is not available about how the LOD can be calculated with high confidence.