Submitted in fulfillment of the academic requirements for the degree of Master of Engineering in Engineering, Durban University of Technology, Durban, South Africa, 2018. / Many separation processes in the chemical and petrochemical industries are energy intensive, and unfortunately, involve a range of solvents that are environmentally harmful and destructive. Alternative, sustainable separation techniques are desired to replace these conventional methods used in the separation of azeotropic as well as close-boiling mixtures, with the intention of reducing energy costs and adverse impact on the environment. In the present study, a new class of solvents called deep eutectic solvents (DESs) of Type III were investigated as alternatives to conventional solvents currently employed in separation processes. DESs are classified as ‘green’ solvents because of a range of favourable properties including lower cost, desirable solubility properties and reduced environmental impact (Abbott et al., 2003b; Smith et al., 2014). The infinite dilution activity coefficients (IDACs) values of 24 solutes – including alk-1-anes, alk-1-enes, alk-1-ynes, cycloalkanes, alkanols, alkylbenzenes, heterocyclics, esters, and ketones – were measured at 313.15, 323.15, 333.15 and 343.15 K by gas-liquid chromatography (GLC) in DESs. The four investigated DESs were as follows: 1) Tetramethylammonium chloride + Glycerol (DES1); 2) Tetramethylammonium chloride + Ethylene Glycerol (DES2); 3) Tetramethylammonium chloride + 1,6 Hexanediol (DES3); and 4) Tetrapropylammonium bromide + 1,6 Hexanediol (DES4). This work focused on the performance of DESs as extractive solvents for selected azeotropic and close-boiling binary mixtures. The two key performance criteria for these extractive solvents – selectivity and capacity – were determined from experimental infinite dilution activity coefficients (IDACs) of various solutes. The effect of solute molecular structure on IDAC values was investigated. Moreover, the effect of varying the hydrogen bond donors (HBDs) in DESs on IDAC values was examined. Partial excess molar enthalpies at infinite dilution were determined from the experimental IDAC data. Moreover, common industrial separation problems were selected to investigate DES potential to separate various mixtures by determining selectivity and capacity at infinite dilution. The results obtained in this study indicate that the use of a long carbon chain HBDs greatly decreases miscibility of DESs with organic solutes. For systems such as n-heptane - toluene, acetone - ethanol, cyclohexane - benzene and n-hexane - benzene systems, DES4 was the best solvent regarding the separation performance index. However, further investigation for DES4 by measurements of vapour-liquid equilibria (VLE) and liquid-liquid equilibria (LLE) data is suggested, as these data would provide additional pertinent information regarding the separation of such mixtures using DES4. The data produced from this study can be used to extend the applicability range of predictive models such as Universal Quasi- Chemical Functional Group Activity Coefficients (UNIFAC) and modified UNIFAC (Do) which are already incorporated in some chemical engineering process simulators. / M

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Made available in DSpace on 2014-06-11T19:29:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2003Bitstream added on 2014-06-13T20:38:17Z : No. of bitstreams: 1 aquino_ft_me_araiq.pdf: 385899 bytes, checksum: 3106d26f4f13b220d6c1372af6c103c2 (MD5) / Os ácidos orgânicos de cadeia curta: acético, propiônico, butírico e valérico tem sido descritos na literatura como sendo fitotóxicos. Esse estudo propõe o monitoramento desses ácidos durante o processo de compostagem de resíduos sólidos domésticos. Foram monitorados três tipos de leiras: leira com revolvimento (LR), leira com material de estrutura (LMe) e leira com cobertura (LC), todas com material de partida proveniente da Usina de Compostagem da cidade de Araraquara, São Paulo. Foram utilizadas três técnicas principais para o monitoramento desses ácidos: Cromatografia Gasosa (CG), Calorimetria Exploratória Diferencial (DSC) e testes de germinação em sementes. A cromatografia demonstrou que esses ácidos são encontrados em baixas concentrações e sua evolução foi curta, já que depois das primeiras amostragens, somente o ácido acético permaneceu, sendo que os demais não foram detectados ou estão abaixo de 5 μg.ml-1. O DSC mostrou-se interessante para avaliação do comportamento da evolução desses ácidos, já que foi apresentada uma influência da matriz sobre um dos analitos. Além disso, o DSC foi uma técnica complementar, que estabeleceu melhor estudo do comportamento do ácido propiônico. Os testes de germinação concluíram que esses ácidos não são fitotóxicos para concentrações de 5-500 μg.ml-1. Quanto à avaliação do composto, esse demonstrou-se apto para aplicação ao solo somente ao final do processo de compostagem. / The short chain organic acids: acetic, propionic, butyric and valeric has been reported in literature as been phytotoxic. This study propose the monitoring these acids during the composting process. It was monitored three types of solid waste dumps: only with turn over (LR); with structure material (LMe) and with a cover layer (LC), all of them with starter material from Composting Plant of Araraquara city, São Paulo. It was utilized three main techniques for monitoring these acids: Gas Chromatography (CG), Differential Scanning Calorimetry (DSC) and seed germination tests. The chromatography demonstrates these acids are present at low concentrations and your evolution was short, after first sample period only acetic acid remains, and the others weren’t detected, or are under 5 μg.ml-1. The DSC showed interesting for the evaluation of the occurence of these acids, that was showed a matrix influence on these analites. Besides, DSC was a complementar technique, that established a better study of propionic acid behaviour. The germination tests concluded these acids aren’t phytotoxic for the range: 5-500 μg.ml-1. To the compost evaluation, it has demonstrates that it was able to soil application only after end of the process.

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From Introduction: Buchu leaf is a very widely used household medicine in South Africa, and is usually administered in the form of a brandy tincture or a vinegar, known as "buchu brandy" and "buchu vinegar" respectively. These preparations have a great reputation in curing diseases of the kidney and urinary tract, and in addition are employed as local applications to bruises, and for the relief of rheumatic pains. We owe its introduction into medicine to the Hottentot, who gave the name "buchu" or "bookoo" to any aromatic herb or shrub which they found suitable for use as a dusting powder.

The metabolism of absorbed xenobiotic compounds in humans results in a mixture of target compounds applicable for analysis, trapped in complex biological matrices. Gas chromatography-mass spectrometry (GC-MS) is a powerful analytical technique that has been successfully applied in the analysis of volatile and semi-volatile compounds from complex biological samples. This is due to the ability of GC-MS to separate different sample constituents at trace levels while providing accurate molecular structural information for the resolved compounds. The complexity of biological specimens and their largely aqueous nature, combined with the physicochemical properties of target analytes resulting from metabolism, greatly precludes direct analysis of biosamples by GC-MS. Traditionally, highly laborious and time consuming sample preparation procedures are performed to isolate and chemically alter target analytes to attain suitable amenity for the detection system. Furthermore, routine analytical procedures in clinical toxicology laboratories are signified by short specimen turn-around times. The commonplace use of GC-MS in modern-day laboratories still suffer from prolonged turn-around times that result from both sample preparation steps and lengthy instrumental analysis. Simplified and cost-effective analytical procedures capable of extracting multiple analytes, with divergent functional groups, from biological matrices in a timely manner are therefore required. To address this issue, this work describes the development of validated extractive-derivatization methods combined with fast GC-MS analysis for expedient and accurate quantitation of different analytes in occupational monitoring and workplace drug testing. Extractive alkylation of acidic analytes phenol, o-cresol, mandelic acid, hippuric acid, and (o-, m-, p-) methylhippuric acid for simultaneous urinary bio-monitoring of occupational exposure to benzene, toluene, ethylbenzene, and xylene, respectively, is performed. Extractive acylation for simultaneous urinary confirmation of basic analytes amphetamine, methamphetamine, norephedrine, methcathinone, ephedrine, methylenedioxyamphetamine (MDA), methylenedioxymethamphetamine (MDMA), methylenedioxyethylamphetamine (MDEA) and N-methyl-1-(3,4 methylenedioxyphenyl)-2-butanamine (MBDB) in workplace drug testing is performed. The successful combination of abovementioned techniques alongside fast GC-MS allows increased sample throughput and decreased turn-around time for routine analysis while maintaining bioanalytical quantitative criteria, as required in a clinical toxicology laboratory setting. / Dissertation (MSc)--University of Pretoria, 2009. / Chemical Pathology / unrestricted

The preputial glands of male nude (nu/nu) mice were analyzed by a combination of electron microscopy and gas chromatography to determine whether or not they are affected, like developing hairs and nails, by the nu/nu genotype. Results of the analyses revealed no differences between the glands of nude and normal male mice in either their ultrastructural characteristics or lipid secretory products.

A Dissertation submitted in fulfillment of the requirements for the degree Master of Science In the Faculty of Sciences at the University of the Witwatersrand, Johannesburg Johannesburg, January 2015 / Three methods, for the analyses of low levels of moisture in gas samples, were developed and optimized. The analytical techniques included Fourier Transform Infrared Spectroscopy (FTIR) and Pulsed Discharge Helium Ionization/Gas Chromatography (PDHID/GC). The methods included the direct analyses of moisture in gas samples using FTIR as well as the analysis of acetylene (C2H2) by FTIR and GC/PDHID. For the latter methods, the purpose was to convert the moisture in a gas sample to C2H2 by hydrolization of the calcium carbide (CaC2) with moisture to C2H2 and then analyze the resulting C2H2 content by FTIR or GC/PDHID. The C2H2 result was then converted back to moisture to obtain the moisture content of the sample. The FTIR moisture method developed provided eleven different wavenumbers for quantitation providing a wide analytical scope, specifically in complex gas matrices, where there is often peak overlap between matrix and moisture. A heated eight meter glass long path gas cell and a mercury cadmium telluride (MCT) detector were utilized. The FTIR method required much greater volumes of sample than the GC method but allowed for direct analysis of moisture without prior conversion to acetylene. Moisture permeation standards were used for calibration and the LOD’s ranged from 0.5 to 1 ppm with quantification possible from 0.5 to 10ppm. For the FTIR C2H2 method various concentration ranges were established from 50 up to 2000 ppm. Three wavenumbers were evaluated for C2H2 and methane was introduced as an internal standard. The use of methane as an internal standard provided better r2 values on the calibration data than for the tests run without internal standard. A gas chromatographic (GC), pulsed discharge helium ionization detector (PDHID) method for the determination of moisture content in small quantities of gases, based on the conversion of the moisture to acetylene (C2H2) prior to analysis, was developed. The method developed on the GC/PDHID for C2H2, provided a quantitation range from 0.6 to 7.7 ppm. Conversion of the moisture to acetylene was achieved by hydrolysing an excess of calcium carbide (CaC2) in a closed reaction vessel with a measured volume of a sample containing a known quantity of moisture. The gaseous reaction mixture was transferred, using helium (He) carrier gas, to a GC/PDHID, set up with “sample injection and heart cut to detector” to prevent matrix disturbances on the PDHID, for analysis. The acetylene concentration values thus obtained were converted back to moisture values and percentage recoveries calculated. A similar conversion process was applied on FTIR. The conversion of moisture to C2H2 using CaC2 was tested and proven to be viable. Quantification was not possible as the available sample holder could not be adequately sealed to prevent air ingress. This led to higher C2H2 values than expected. This process can be optimized by the design and production of a sealed sample holder.

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