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Method development for determination and removal of the selected steroids from water sources in selected areas around the Vaal River in South Africa using High performance Liquid Chromatography, Macadamia Activated Carbon and Solid Phase ExtractionKhotha, Doctor Elias January 2018 (has links)
M. Tech (Department of Chemistry, Faculty of Applied and Computer Sciences) Vaal University of Technology. / A simple and rapid method for determination of estrone (E1) and β-estradiol (E2) was developed and validated using high performance liquid chromatography (HPLC). The solutions of standards and sample were prepared with distilled water. HPLC separation was performed in isocratic method 50/50 (water/methanol) using 4.6 mm x 250 mm id film thickness 5 µm) XDB-C18 capillary column, detector DAD, UV on 254 nm, temperature 20 ºC with flow rate of 2 mL/min, sample volume 20 µL and run time of 10 min. Calibration curves were linear between concentration range 1.0 - 15.0 ppm. The method was validated for limit of detection and quantification, linearity, precision, trueness and specificity. Also the method was applied to directly and easily to the analysis of the E1 and E2. Adsorption experiments were carried out in batch mode using multistirrer in a series of Erlenmeyer flasks of 50 ml capacity covered to prevent contamination having concentration ranges of E1 and E2 from 1 to 10 mg/L with adsorbent dose range 0.01 to 1 g at pH range 1 to 10 and temperature range 15°C to 35°C, placed on multistirrer. The results of the batch studies showed that simultaneous adsorption shows the maximum percent (91%) removal of E1 and (86 %) E2 at optimum temperature 25 °C of adsorbent dose 0.1 g, and pH 7. The mechanism, isotherms and kinetics of removal of two endocrine disrupting chemicals, estrone (E1) and β-estradiol (E2) by activated carbon adsorption were investigated in an agitated non-flow batch adsorption studies. Mathematical models were used to describe the adsorption phenomenon with the kinetic and thermodynamic parameters evaluated using the adsorption equilibrium data at varying temperatures.
Higher adsorption rates were achieved at acidic to neutral pH ranges, with the sorption kinetic data showing a good fit to the pseudo second order rate equation and the Langmuir adsorption isotherm model for both E1 and E2. The Gibbs free energy were –16.68 kJ/mol and –17.34 kJ/mol for E1 and E2 respectively. The values of enthalpy for both E1 (84.50 kJ/mol) and E2 (90 kJ/mol) indicated a chemical nature of the sorption process. Both the isotherm and thermodynamic data obtained all supported the mechanism of adsorption of E1 and E2 to be mainly chemisorption’s supported by some physical attractions.
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Removal of selected chlorinated phenolic compounds from water sources in Vaal Triangle using HPLC, Macadamia nutshell activated carbon and solid phase extractionMachedi, Sechaba 12 1900 (has links)
M. Tech (Department of Chemistry, Faculty of Applied and Computer Sciences) Vaal University of Technology. / In this study, analytical method for determining the chlorinated phenols in water was developed using High Performance Liquid Chromatography. The following four compounds which are 2, 4, 6- Trichlorophenol (2, 4, 6 TCP), 3-chlorophenol (3CP), 2, 4- Dichlorophenol (2, 4 DCP) and 4-chloro-3-methylphenol (4C3MP) were identified and
quantified with a High Performance Liquid Chromatography (HPLC). The validation parameters tested were,: linearity, trueness, precision, detection limit of quantitation, sensitivity, specificity, selectivity. The linear calibration ranges of five standard solution from 1-10 ppm. The linearity ranges between 0.9298-0.9813. The activated carbon based on the waste macadamia nutshell activated carbon (MAC) was investigated for its potential uses as an adsorbent for chlorinated phenols removal and compared with grafted macadamia nutshell activated carbon (GMAC). The adsorbent was characterized with Fourier transform infrared spectrophotometer (FTIR), scanning electron microscope (SEM) and thermo gravimetric analysis (TGA). The parameters such as pH, temperature, contact time, concentration and adsorbent were investigated by adsorption technique. The strata C18E has been used before for the same reason and therefore the research was based on mimic the functional group of solid phase extraction (SPE) into macadamia activated carbon (MAC). The functional groups in SPE C18E are benzene and octadecyl. MAC was grafted with strata C18E functional groups to compare its potential with the SPE. The pseudo-first-order and pseudo-second-order kinetic models were applied to verify the experimental data. The pseudo-second order exhibited the best fit for the kinetic studies for MAC adsorption. Chemical removal of chlorinated phenols from wastewater is necessary to reduce harmful products on the environment and human health. Chlorinated phenols have been previously listed as some of the highest priority contaminants and as well as mainly important capability carcinogenic toxins released from chemical plants. Their availability in water supplies was perceived by their bad taste and smell. The acceptable chlorinated phenols concentration in portable water is 1 (mg/l) base on the approval of world health organization. The permanent checking of chlorinated phenols in environmental samples has a greater significance and stresses highly effectiveness, common selectively and great sensitively methods. The maximum uptake of Phenol using weighed mass of MAC was found to be 78 % and for GMAC was 84% for both 2,4,6TCP. t=250 min, pH=5, Co=1mg/l, T = 25 oC and m = 0.3 g/l were the optimum condition for Phenol-MAC system and GMAC system. Over all analysis of equilibrium model analysis indicates the fitness of Langmuir isotherm model to Phenol MAC adsorption system, suggesting a monolayer adsorption of phenol on the surface of MAC. Phenol adsorption capacity of MAC was found to be decreasing with increase in temperature suggesting that the adsorption process was exothermic in nature, which was further supported by the negative values of change in enthalpy. Characterization of MAC and GMAC confirmed the mesoporous texture, highly carbonaceous nature and a higher effective surface area of 912 m2/g. The highest phenol uptake capacity of GMAC was found to be 8.0049 mg/g. The optimal conditions for various process parameters are t = 250 min, pH=5, Co=1mg/l, T = 25 oC and m = 0.3 g/l were the optimum condition for Phenol-GMAC system. Like Phenol-MAC system, the kinetics studies confirmed that Phenol-GMAC adsorption system can be described by pseudo- second-order kinetics model. Equilibrium model analysis indicates the fitness of Langmuir isotherm model to Phenol-MAC adsorption system, suggesting a monolayer adsorption of phenol on the surface of GMAC. Phenol adsorption capacity of GMAC was found to be decreasing with increase in temperature suggesting that the adsorption process was exothermic in nature, which was further supported by the negative values of change in enthalpy. The negative values of Gibb’s free energy suggested that adsorption of phenol onto GMAC was a spontaneous process.
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Separation of Transition Metal Ions by HPLC, Using UV-VIS DetectionLien, Wan-Fu 08 1900 (has links)
HPLC has been used and can quickly determine several ions simultaneously. The method of determination described for transition metals [Cr(III), Fe(III), Ni(II), Co(II), Cu(II), Zn(II), Cd(II), Mn(II)] and [Ca(II), Pb(II)] using HPLC with UV-VIS detection is better than the PAR complexation method commonly used. The effects of both eluent pH and detector wavelength were investigated. Results from using different pHs and wavelengths, optional analytical conditions for the separation of [Ni(II), Co(II), Cu(II)], [Cr(III), Fe(III), Ca(II), Ni(II), Cu(II)], and [Ca(II), Zn(II), Pb(II)] in one injection, respectively, are described. The influence of adding different concentrations of Na_2EDTA solvent to the sample is shown. Detection limits, linear range, and the comparisons between this study and a post-column PAR method are given.
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Incorporacao e liberacao de resveratrol em hidrogeis polimericos / Resveratrol immobilization and release in polymeric hydrogelsMOMESSO, ROBERTA G.R.A.P. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:27:38Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:21Z (GMT). No. of bitstreams: 0 / Resveratrol (3, 4, 5-trihidroxiestilbeno) é um polifenol produzido por uma grande variedade de plantas em resposta ao estresse e encontrado predominantemente em cascas de uvas. Este princípio ativo apresenta vários benefícios à saúde, como a capacidade antioxidante, relacionada à prevenção de diversos tipos de câncer e do envelhecimento precoce da pele. No entanto, apresenta baixa biodisponibilidade quando administrado por via oral, o que torna interessante sua aplicação tópica. O principal objetivo deste trabalho foi a incorporação de resveratrol em hidrogéis poliméricos para obtenção de um sistema de liberação utilizado topicamente contra o desenvolvimento de desordens cutâneas, como o envelhecimento cutâneo e o câncer de pele. As matrizes poliméricas compostas por poli(N-vinil-2-pirrolidona) (PVP), poli(etileno glicol) (PEG) e ágar ou PVP e propano-1,2,3-triol (glicerina) e irradiadas a 20 kGy foram caracterizadas pelos ensaios de fração gel e intumescimento; sua biocompatibilidade preliminar foi avaliada in vitro por meio do ensaio de citotoxicidade utilizando o método de incorporação do vermelho neutro. Devido à baixa solubilidade do resveratrol em água, verificou-se o efeito da adição de 2% de etanol às matrizes. Todas as matrizes estudadas, contendo ou não álcool, apresentaram alto grau de reticulação, capacidade de intumescimento e não apresentaram toxicidade em ensaio preliminar de biocompatibilidade. Os dispositivos foram obtidos pela incorporação de resveratrol nas matrizes poliméricas, realizada de forma direta e indireta, ou seja, antes e após irradiação, respectivamente. Os dispositivos obtidos pelo método direto foram submetidos aos ensaios de fração gel, intumescimento e citotoxicidade e apresentaram-se semelhantes às respectivas matrizes. Os dispositivos contendo 0,05% de resveratrol obtidos pelo método direto e os dispositivos contendo 0,1% de resveratrol obtidos pelo método indireto foram submetidos ao ensaio de cinética de liberação durante 24 h. A quantificação do resveratrol liberado foi realizada por cromatografia líquida de alta eficiência (HPLC). Apenas os dispositivos obtidos pelo método indireto apresentaram capacidade de liberar o resveratrol incorporado, que apresentou capacidade antioxidante após liberação. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Novel approaches for the chromatographic and electrophoretic separation of moleculesMeyer, Amanda R. January 1900 (has links)
Doctor of Philosophy / Department of Chemistry / Christopher T. Culbertson / High-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) are two well-established analytical separation techniques that are continuously being adapted for performing distinctive separations and analyses of multitudes of complex and/or unique samples. Since their introduction, these techniques have been pivotal in the discovery, analysis, and understanding of a variety of samples and still prove to be key analytical tools for biological investigation.
Using these techniques, one can obtain a wide-range of valuable sample information from the hydrophobicity and molecular weights to size and charge distributions. Furthermore, these techniques allow for sample analysis, purification, and collection for additional sample analysis, such as mass spectrometry analysis. My doctoral dissertation encompasses the full scope of these two techniques and novel approaches for the investigation of distinct, relevant samples.
Described herein is the fabrication of glass microfluidic devices used for CE and their diversity for numerous investigations. Chapter 2 shows that the resolution of the photomasks used in microchip fabrication does not alter the separation efficiency of the devices, as the separations remain diffusion-limited. Using an in-house built capillary electrophoresis system, wheat proteins were separated more than 25% faster than previously reported in literature, and the electropherograms used for sample varietal identification. The fabrication of a robust, portable CE system capable of performing biological analysis in microgravity and hypergravity environments is also discussed. The need for and features necessary to achieve a reliable, robust, automated system is further described in Chapter 4. Isolation and analysis of the pea aphid (Acyrthosiphon pisum) salivary secretions was completed for the first time using HPLC. By altering the aphid environment and the sample treatment parameters, sample concentrations were increased above the limit of detection. Coupled with mass spectrometry, identification of pea aphid salivary proteins such as exopeptidase, angiotensin converting enzyme, and Buchnera proteins has been achieved. Finally, a simplified contact conductivity detection system for the detection of jurkat cells was developed that surpasses current, complex optical systems. The experiments described in this dissertation demonstrate novel approaches for the preparation, separation, analysis, and identification of a wide variety of common, and uncommon, samples.
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Multidimensional analytical techniques for the characterization of aliphatic polyestersPretorius, Nadine Odette 03 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Complex polymers are defined by their distributive properties with respect to molecular weight, chemical
composition, functionality and molecular topology. As a result, polymer properties are very frequently
determined not only by one of these entities but by the correlation of two or more distributions. Aliphatic
polyesters are industrially implemented in high performance coatings, paints and varnishes. However, it is
typically difficult to correlate the resulting properties with the synthesis parameters as these polymers vary in
reactivity and application properties. Copolyester synthesis by direct polyesterification is often assumed to
produce randomized products due to the mechanisms involved in stepwise polymerization. The formation of
cyclic products by intramolecular reactions of hydroxyl (OH) and carboxylic (COOH) functional groups, sidereactions
such as transesterification, alcoholysis, and ester-ester interchange allow even further
randomization, enabling a highly complex system. Therefore, in addition to molecular weight distribution,
polyesters exhibit chemical composition, functionality type as well as branching distributions, classifying them
as complex polymeric systems. The different methods of polymer chromatography in combination with
sophisticated spectrometry techniques are useful tools for enabling the full description of the molecular
heterogeneity of these complex polyesters. The present study entails method development of different
modes of chromatography and mass spectrometry along with their combination, to facilitate the analysis of
the various distributions of two model polyester systems, phthalic and maleic anhydride, respectively, in
combination with propylene glycol. Gradient HPLC analysis enabled an oligomeric separation based on
chemical composition of the respective anhydride/propylene glycol samples. Its off-line coupling to MALDITOF
MS and ESI-QTOF MS revealed the presence of several distributions of varying endgroup functionality
type and molecular weight distributions at different intervals throughout the polymerization. In addition, online
gradient HPLC x size exclusion chromatography (2D-LC) was conducted to obtain the dual chemical
composition-molecular weight (CCD-MWD) distribution. The combination of the different coupling techniques
provided the opportunity to a more in-depth analysis of the structure-property relationships. / AFRIKAANSE OPSOMMING: Komplekse polimere word gedefinieer deur hul verdelings eienskappe ten opsigte van molekulêre massa,
chemiese samestelling, funksionaliteit en molekulêre topologie. Gevolglik, word hul eienskappe dikwels
bepaal deur nie net een van hierdie entiteite nie, maar ‘n korrelasie van twee of meer verdelings. Alifatiese
poliësters word industrieel geϊmplimenteer in hoë werkverrigting bestrykings, verwe en politoere, dog is dit
tipies moeilik om die uiteinde eienskappe met die verwante sintese parameters te korrelleer, aangesien die
polimere varieer in reaktiviteit en toepassingseienskappe. Ko-poliëster sintese vanaf direkte poliësterivering
word dikwels aanvaar om willekeurige produkte op te lewer as gevolg van die meganismes wat betrokke is
tydens trapgroei polimerisasie. Die produsering van sikliese produkte weens intra-molekulêre reaksies van
hidroksiel(OH) en karboksiel (COOH) verwante funksionele groepe, newereaksies soos transverestering,
alkoholise en ester-ester verwisseling, het verdere ewekansigmaking tot gevolg wat ‘n hoog
gekomplekseerde sisteem tot gevolg het. Benewens die molekulere massa verdeling, vertoon poliësters
dus chemiese samestelling, funksionaliteit tipe so wel as vertakkings verdeling wat hul as komplekse
polimeer sisteme klassifiseer. Die verskillende metodes van polimeer chromatografie in kombinasie met
gesofistikeerde spektrometriese tegnieke dien as nuttige bronne vir die volledige beskrywing wat betref die
molekulêre heterogeniteit van komplekse poliesters. Die huidige studie stel metode ontwikkeling van
verskillende modus van chromatografie, massa spektrometrie sowel as hul aaneenvoeging bekend, om die
die verskillende verdelings van twee model poliester sisteme, ftaal- en maleϊensuuranhidried onderskeidelik
in kombinasie met propileenglikol, suksesvol te analiseer. Gradiënt hoë-druk vloeistof chromatografie
(HPLC) analise het ‘n oligomeriese skeiding, gebaseer op die chemiese samestelling van die verskeie
anhidried /propileenglikol monsters, opgelewer. Die nie-gekoppelde skakeling met matriks-assisteerdelaser/
desorpsie-ionisasie tyd-van-vlug (MALDI-TOF) en elektron-sproei-ionisasie kwadrupool-tyd-van-vlug
(ESI-QTOF) massa spektrometrie het die teenwoordigheid van verskeie verdelings van varieërende
endgroep funksionaliteit tipe en molekulêre verdelings by verskillende intervalle tydens die polimerisasie aan
die lig gebring. Gekoppelde skakeling van gradient HPLC en grootte uitsluitings chromatografie is ook uitgevoer om die tweedelige chemiese samestelling-molekulere massa verdeling te bepaal. Aaneenvoeging
van die verskeie skakelings tegnieke het die geleentheid gebied om ‘n deeglike studie van die struktuureienskappe
verhoudinge suksesvol uit te voer.
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Evaluation of pressure- and electrodriven separation techniques for the determination of phenolic compounds in wineDe Villiers, A. J. (Andre Joubert) 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The phenolic content of wine is responsible for determining characteristics such as the
organoleptic qualities, colour stability, ageing properties and health-beneficial effects
associated with wine. The aim ofthis study was to investigate the possibilities offered by
capillary electrophoresis (CE) as an alternative separation technique to high performance
liquid chromatography (HPLC) for the analysis of polyphenols in wine. The complexity
of wine samples was the cause that neither technique was capable of a satisfactory singlestep
analysis of wine. Suitable sample preparation techniques such as Sephadex- and Sep-
Pak fractionation and ether extraction of wine polyphenols were investigated. These
techniques did not, however, prove to be universal. A novel form of sample preparation
namely a process analogous to lyophylization used to separate wine volatiles from nonvolatiles
was introduced.
The versatility of CE was further investigated in an attempt to eliminate the need for
sample preparation. The use of polyvinylalcohol (PVA) coated capillaries, micellar
electrokinetic chromatography (MEKC) and capillary gel electrophoresis (CGE) were
investigated in this regard. Although none of these techniques could offer conclusive
results, useful applications were forthcoming and routes for further investigation were
outlined. Liquid chromatography coupled to electro spray ionisation mass spectroscopy
(LC-ESI-MS) and capillary electrophoresis coupled to electro spray ionisation mass
spectroscopy (CE-ESI-MS) were compared for the analysis of polyphenols in wine.
While the latter technique could not produce sufficient separation compared to the
former, future development ofCE-ESI-MS should make it a powerful technique for these
analyses. / AFRIKAANSE OPSOMMING: Die fenoliese komponente in wyn speel 'n bepalende rol by eienskappe soos die
organoleptiese karakter, kleur stabiliteit, verouderingspotensiaal en gesondheids-voordele
wat met wyn geassosieër word. Die doel van hierdie projek was om ondersoek in te stel
na die potensiaal wat kapillêre elektroforese (CE, "capillary electrophoresis") as 'n
alternatiewe skeidingstegniek teenoor hoë druk vloeistof chromatografie (HDVC) vir die
analise van die polifenole in wyn bied. Die kompleksiteit van wyn monsters is van so 'n
aard dat 'n bevredigend enkelstap analise met geeneen van die tegnieke moontlik is nie.
Gepaste monster-voorbereidingstappe soos Sephadex- en Sep-Pak fraksionering asook
eter ekstraksie van die polifenole in wyn is ondersoek. Geeneen van die tegnieke was
egter universeel toepaslik nie. 'n Nuwe metode van monster-voorbereiding, naamlik 'n
proses analoog aan liofilisasie wat gebruik word om die wyn te skei in vlugtige en nievlugtige
komponente is gedemonstreer.
Die veelsydigheid van CE was gevolglik ondersoek in 'n poging om
monstervoorbereiding uit te skakel. Die gebruik van polyvinielalkohol-(pVA) bedekte
kapillêre, missellêre elektrokinetiese chromatografie (MEKC) en kapillêre gel
elektroforese (CGE, "capillary gel electrophoresis) is in hierdie verband ondersoek.
Alhoewel geeneen van hierdie tegnieke onweerlegbare resultate gelewer het nie, het
bruikbare toepassings hieruit voortgespruit en is die grondslag vir verdere navorsing gelê.
Vloeistof chromatografie gekoppel aan eIektrosproei ionisasie massaspektroskopie (LCESI-
MS) en kapillêre elektroforese gekoppel aan elektrosproei ionisasie massaspektroskopie
(CE-ESI-MS) is vergelyk vir die analise van polifenole in wyn. Alhoewel
laasgenoemde tegniek onvoldoende skeiding lewer vergeleke met eersgenoemde, behoort
toekomstige ontwikkelinge op die gebied van CE-ESI-MS dit 'n kragtige tegniek vir die
analise van hierdie monsters te maak.
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Amino acid analysis in wines by liquid chromatography : UV and fluorescence detection without sample enrichmentDouglas, C. A. (Claire Anne) 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: In this study, the analysis of ammo acids usmg High Performance Liquid
Chromatography (HPLC) with pre-column derivatisation was optimised. The
derivatisation reagents include o-phthaldialdehyde (OPA), 9-
fluorenylmethylchloroformate (FMOC) and iodoacetic acid (IDA). Detection was
performed using UV and fluorescence in series. The developed method was utilised
for the analysis and quantitation of amino acids in eighteen wines. The application of
chemometric data evaluation was initiated. / AFRIKAANSE OPSOMMING: Hierdie ondersoek behels die optimisering van die aminosuuranalise deur gebruik te
maak van Hoë Druk Vloeistof Chromatografie (HDVC) in kombinasie met pre-kolom
derivatisering. Die derivativatiserings reagense sluit in o-phthaldialdehied (OPA), 9-
fluorenielmetielchloroformaat (FMOC) en jodoasynsuur (IDA). Deteksie is gedoen
deur gebruik gemaak van 'n ultraviolet (UV) en 'n fluorosensie detektor in serie. Die
metode sodoende ontwikkel is gebruik vir die analise en kwantifisering van aminosure
in agtien wyne. Die toepassing van chemometriese data evaluasie is ook geïnisieer.
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A study on the reversible photo-induced isomerisation of platinum(II) and palladium(II) complexes of the N,N-dialkyl-N’-acyl(aroyl)thioureas with reversed-phase HPLC separation from related rhodium(III), ruthenium(III) and iridium(III) complexesNkabyo, Henry Ane 04 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: See item for full text / AFRIKAANSE OPSOMMING: Sien item vir volteks
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Design, synthesis and characterization of ruthenium(II) and rhenium(I)complexes with functionalized ligands for photo-and electrochemi-luminescence, solvatochromism, molecular recognition and HPLCseparation studiesLi, Meijin., 李梅金. January 2006 (has links)
published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy
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