Dissertations / Theses: 'Analytical Chemistry Techniques'

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Olsson, Jeanette. "New Techniques for Chiral Separations." Doctoral thesis, Karlstad : Faculty of Technology and Science, Chemistry, Karlstads universitet, 2008. http://www.diva-portal.org/kau/abstract.xsql?dbid=1594.

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Altun, Zeki. "New Techniques for Sample Preparation in Analytical Chemistry." Licentiate thesis, Karlstad University, Division for Chemistry, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-1374.

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Sample preparation is often a bottleneck in systems for chemical analysis. The aim of this work was to investigate and develop new techniques to address some of the shortcomings of current sample preparation methods. The goal has been to provide full automation, on-line coupling to detection systems, short sample preparation times and high-throughput.

A new technique for sample preparation that can be connected on-line to liquid chromatography (LC) and gas chromatography (GC) has been developed. Microextraction in packed syringe (MEPS) is a new solid-phase extraction (SPE) technique that is miniaturized and can be fully automated. In MEPS approximately 1 mg of sorbent material is inserted into a gas tight syringe (100-250 μL) as a plug. Sample preparation takes place on the packed bed. Evaluation of the technique was done by the determination of local anaesthetics in human plasma samples using MEPS on-line with LC and tandem mass spectrometry (MS-MS). MEPS connected to an autosampler was fully automated and clean-up of the samples took one minute. In addition, in the case of plasma samples the same plug of sorbent could be used for about 100 extractions before it was discarded.

A further aim of this work was to increase sample preparation throughput. To do that disposable pipette tips were packed with a plug of porous polymer monoliths as sample adsorbent and were then used in connection with 96-well plates and LC-MS-MS. When roscovitine in human plasma and water samples was used as model substance, a 96-plate was handled in two minutes.

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Starkey, Jason A. "Biochemical applications of microcolumn separation techniques." [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3278220.

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Thesis (Ph. D.)--Indiana University, Dept. of Chemistry, 2007.
Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 5919. Adviser: Milos V. Novotny. Title from dissertation home page (viewed May 9, 2008).

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Simjee, Nafeesa. "Development of microelectrode techniques for analytical measurements." Thesis, University of Warwick, 2003. http://wrap.warwick.ac.uk/2664/.

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This thesis describes the development and application of hydrodynamic modulation voltammetric (HMV) techniques coupled to ultramicroelectrodes (UMEs) that possess intrinsically high mass transport rates in quiescent solutions. This study demonstrates that the well defined convective-diffusive conditions of the microjet electrode (MJE) arrangement allows mass transport to be enhanced by almost two orders of magnitude compared to a 25 mm diameter disc-shaped UME. The MJE comprises a nozzle which is used to deliver solution to a UME surface at high velocity. Scanning electrochemical microscopy (SECM) with small UMEs has been used to image the hydrodynamics of the jet system with high precision. Variations in local mass transport for both IrCl63- and Fe(CN)64- oxidation at a range of flow rates has been observed at various positions within the impinging jet and the stagnation zone has been thoroughly characterised under a variety of experimental conditions. Agreement has been found between experiment and theory for voltammetric data recorded with the nozzle and UME aligned in the stagnation zone, for a range of viscous solutions examined. By modulating the mass transport rate to the surface of an UME, in the MJE arrangement, by the introduction of a rotating blade between the end of the nozzle and the UME, it was possible to enhance the current sensitivity of the system. Trace level detection, to 2 x 10-7 mol dm-3 IrCl63- solution, was readily facilitated. This type of HMV experiment has utilised two methods to provide the reference signal for phase-sensitive detection of the current signal, involving either a dual-disc electrode or a single UME coupled to an LED detection system. Both HMV methods have been shown to work well.

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Fancy, Sally-Ann. "Physical and analytical applications of ion trapping techniques." Thesis, University of Kent, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311226.

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Sartoros, Christine. "Application of artificial intelligence techniques for inductively coupled plasma spectrometry." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0016/NQ44574.pdf.

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Haines, Emma Sara. "The application of chemometric techniques to spectroscopic data." Thesis, University of Hull, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301636.

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Kaza, Lakshmi S. "Novel Thermal Analytical Techniques to Characterize Drugs and Drug Delivery." Cleveland State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=csu1317258017.

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Cacha, Brian Joseph Gonda. "Metallic nanoparticle deposition techniques for enhanced organic photovoltaic cells." Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1598627.

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Energy generation via organic photovoltaic (OPV) cells provide many advantages over alternative processes including flexibility and price. However, more efficient OPVs are required in order to be competitive for applications. One way to enhance efficiency is through manipulation of exciton mechanisms within the OPV, for example by inserting a thin film of bathocuproine (BCP) and gold nanoparticles between the C₆₀/Al and ZnPc/ITO interfaces, respectively. We find that BCP increases efficiencies by 330% due to gains of open circuit voltage (V_oc) by 160% and short circuit current (J_sc) by 130%. However, these gains are complicated by the anomalous photovoltaic effect and an internal chemical potential. Exploration in the tuning of metallic nanoparticle deposition on ITO was done through four techniques. Drop casting Ag nanoparticle solution showed arduous control on deposited morphology. Spin-coating deposited very low densities of nanoparticles. Drop casting and spin-coating methods showed arduous control on Ag nanoparticle morphology due to clustering and low deposition density, respectively. Sputtered gold on glass was initially created to aid the adherence of Ag nanoparticles but instead showed a quick way to deposit aggregated gold nanoparticles. Electrodeposition of gold nanoparticles (AuNP) proved a quick method to tune nanoparticle morphology on ITO substrates. Control of deposition parameters affected AuNP size and distribution. AFM images of electrodeposited AuNPs showed sizes ranging from 39 to 58 nm. UV-Vis spectroscopy showed the presence of localized plasmon resonance through absorption peaks ranging from 503 to 614 nm. A linear correlation between electrodeposited AuNP size and peak absorbance was seen with a slope of 3.26 wavelength(nm)/diameter(nm).

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Pekay, Lars Arthur. "Investigations in coal chemistry : advancements of analytical techniques and reactive oxidative desulfurization /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487760357819292.

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Kong, Cher Rong Matthew. "Contactless liquid flow control for miniaturised analytical techniques on continually rotating centrifugal microfluidic platforms." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=117150.

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In an industrial society it is critical that techniques be developed for the measurement of chemical species in the environment, in humans and as both intended and unintended products of manufacturing. Initially, these techniques were developed around sophisticated instruments and often involved complex procedures. It is obviously advantageous if the cost of analyses can be reduced and the experimental procedures simplified, while still maintaining the quality of the data collected. Furthermore, it is often desirable to have measurements performed rapidly, with on-site measurement sometimes deemed useful or even essential. All of these desirable outcomes may, in some cases, be obtained by miniaturisation. The interest in miniaturisation has led to rapid growth of the field of microfluidics, an area of study which involves using small volumes of liquids, often with detection systems specifically tailored to these reduced volumes. Microfluidic systems must have some way of moving liquids through various stages of chemical or physical processes. One particularly interesting pumping method involves the use of centrifugal force, which eliminates the need for pumps and minimises connections to the platform on which the analysis is done. Up to this point, centrifugal systems have generally been constrained to a limited number of sequential analytical steps as liquid could only flow in the direction demanded by the applied centrifugal force.In this thesis, a variety of liquid manipulation techniques on centrifugal microfluidic platforms were developed and characterised. These techniques were used to miniaturise standard classical analytical methods and implement them on centrifugal microfluidic platforms with the goal of monitoring environmentally important compounds such as aqueous sulfide. A two-phase liquid displacement pumping technique and a pneumatic-centrifugal pumping technique are demonstrated and presented. The developed pneumatic-centrifugal system was used to significantly increase the toolbox of capabilities for centrifugal microfluidic platforms, simultaneously enabling critical microfluidic operations such as valveless liquid transfer, metering, liquid flow switching, agitative micromixing, and liquid recirculation. This technique is based on contactless implementation of pneumatic pressure using compressed air on a continually rotating centrifugal microfluidic platform, thereby enabling complete liquid flow control by combining the effects of pneumatic pressure and centrifugal force.This new type of pneumatically enhanced centrifugal microfluidic platform greatly simplifies the fabrication process by minimising valving requirements, as well as improving efficiency by performing analyses in a highly automated manner. The pneumatic approach was applied to an on-disk calibration and spectrophotometric measurement using the method of standard additions. Similarly, another pneumatically enhanced platform was developed for performing liquid-liquid extractions between an aqueous phase and an organic phase, demonstrating that these centrifugal platforms are not only capable of performing complex multi-step reactions, but also multi-cycle reactions and processes. Finally, an application-specific pneumatically enhanced centrifugal platform was developed for the spectrophotometric determination of aqueous hydrogen sulfide.All of the developed analytical methods only required small sample and reagent volumes, are highly automated and convenient, and have the potential to be performed in a field environment without the need for highly trained personnel.
Dans notre société industrielle, la conception de techniques pour la quantification d'espèces chimiques dans l'environnement, les humains et les dérivés de la production manufacturière est primordiale. Au départ, ces techniques avaient été élaborées à partir d'instruments sophistiqués et se basaient sur des procédures complexes. Il serait donc avantageux de pouvoir réduire les coûts d'analyse et simplifier les procédures expérimentales, tout en maintenant un niveau élevé de la qualité des données recueillies. De plus, il est souvent souhaitable de pouvoir effectuer ces mesures rapidement, et si possible sur le site où l'échantillon à analyser est recueilli. Toutes ces caractéristiques bénéfiques des méthodes analytiques peuvent être obtenues, dans certains cas, à travers la miniaturisation. L'intérêt pour la miniaturisation a mené à une croissance rapide des systèmes microfluidiques, un domaine d'études qui se concentre sur l'utilisation de petits volumes de liquide et des systèmes de détection spécialement adaptés à ces volumes réduits. Tout système microfluidique doit intégrer une méthode de transfert des liquides à travers différentes étapes de traitements chimiques ou physiques. Une méthode de pompage particulièrement intéressante utilise la force centrifuge, ce qui permet d'éliminer l'utilisation de pompes ou connections externes au système où s'effectue l'analyse chimique. Jusqu'à présent, les systèmes employant la force centrifuge ont été limités par le nombre d'étapes analytiques consécutives, le liquide ne pouvant se déplacer que dans une seule direction définie par la force centrifuge appliquée.Pour cette thèse, plusieurs techniques de manipulation des liquides sur un système microfluidique à base de force centrifuge ont été dévelopées et caractérisées. Ces techniques ont été utilisées pour miniaturiser les méthodes analytiques classiques pour ensuite les intégrer à des plateformes microfluidiques à base de force centrifuge, l'objectif final étant la surveillance d'espèces chimiques dans l'environnement. Une technique de pompage par déplacement de deux phases liquides et une technique de pompage pneumatique à base de force centrifuge sont démontrées. La technique pneumatique à base de force centrifuge qui a été développée augmente de façon significative les capacités de la boîte à outils des systèmes microfluidiques à base de force centrifuge. Ce nouveau système permet d'effectuer simultanément des opérations essentielles dans les systèmes microfluidiques telles que le transfert de liquides sans valves, les dosages, la commutation du débit des liquides, les micromélanges par agitation ainsi que la recirculation des liquides. Cette technique se base sur l'application sans contact d'une pression pneumatique en utilisant de l'air comprimé sur un système microfluidique à base de force centrifuge en rotation constante. Ceci permet un contrôle complet du débit des liquides en combinant les effets de la pression pneumatique et de la force centrifuge. Le processus de fabrication de ce nouveau système est grandement simplifié par l'ajout du système pneumatique car cela diminue le nombre de valves à intégrer dans le système. De plus, son efficacité est accrue grâce à la possibilité d'effectuer des analyses de façon automatisée. Cette approche pneumatique a été appliquée à des mesures spectrophotométriques par la méthode des additions connues effectuées directement sur le disque. Dans le même ordre d'idées, un autre système employant la fonction pneumatique a été développé pour effectuer des extractions liquide-liquide entre une phase liquide et une phase organique. Ceci a démontré que la plateforme centrifuge est capable non seulement d'effectuer des réactions chimiques complexes en plusieurs étapes, mais aussi de répéter les cycles de réactions et autres processus.

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Hargreaves, Elaine Carol. "Applications of surface vibrational spectroscopic techniques." Thesis, University of Nottingham, 1997. http://eprints.nottingham.ac.uk/28593/.

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An advanced Electron Energy Loss Spectrometer has been used to study the formation of 3,3,3-trifluoropropylidyne on Pt (111). This has been compared to the results from the same system using the complementary vibrational spectroscopic technique of Reflection Absorption Infrared Spectroscopy (RAIRS). This study demonstrates the improved resolution of the new spectrometer. The thermal decomposition products, CF3 and CF2 have been detected in the Electron Energy Loss (EEL) spectra. The RAIR spectra of carbon monoxide on Cu (111) have been recorded using synchrotron radiation. An optical accessory has been used to record the RAIR spectra at an incident angle of 20°. The results have been compared to an incident angle of 87°. At 20° no conventional absorption band at 339 cm-l was observed and an anti absorption band at 274 em-l of similar magnitude to that at 87° was seen. This has confirmed the involvement of the parallel electric field in the observation of antiabsorption bands. The EEL spectra of hydrogen and deuterium adsorbed on Pt (111) at 160 K have been recorded. The data has been interpreted using the Nearest Neighbour Central Force Constant (NNCFC) model in terms of 3- fold and 2-fold bridging sites. It is the 2-fold site which offers the more complete assignment of the vibrational bands observed.

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Gimblett, Brian James. "The application of artificial intelligence techniques to data interpretation in analytical chemistry." Thesis, University of Salford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395862.

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Avula, Satya Girish Chandra. "Lipidomics of Algae and Human Plasma by Chromatography and Mass Spectrometry Techniques." Cleveland State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=csu1470822409.

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Seetohul, L. Nitin. "Novel applications of optical analytical techniques." Thesis, Teesside University, 2009. http://hdl.handle.net/10149/117905.

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Novel applications of optical analytical techniques have been demonstrated in three general areas, namely application of broadband cavity enhanced absorption spectroscopy (BBCEAS) to the detection of liquid phase analytes, the use of total luminescence spectroscopy to discriminate between different type of teas and the development of an optical sensor to detect ammonia gas, based on the fluorescence quenching of a dye immobilised in a sol gel matrix. A simple BBCEAS setup has been developed with a view to perform sensitive visible wavelength measurements on liquid phase solutions. In the present work a simple low-cost experimental setup has been demonstrated for the measurement of the visible spectra of representative liquid-phase analytes in a 2 mm quartz cuvette placed at normal incidence to the cavity mirrors. Measurements on Ho3+ and sudan black with a white LED and the R ≥ 0.99 mirrors covered a broad wavelength range (~250 nm) and represents the largest wavelength range covered to date in a single BBCEAS experiment. The sensitivity of the technique as determined by the best αmin value was 5.1 x 10-5 cm-1 and was obtained using the R ≥ 0.99 mirrors. The best limit of detection (LOD) for the strong absorber brilliant blue-R, was approximately 620 pM. The optical setup was then optimised for the application of BBCEAS detection to an HPLC system. A 1 cm pathlength HPLC cell with a nominal volume of 70 ml was used in this study. The cavity was formed by two R ≥ 0.99 plano-concave mirrors with a bandwidth of ~ 420 – 670 nm. Two analytes rhodamine 6G and rhodamine B were chosen for separation by HPLC, as they were chemically similar species with distinctive visible spectra and would co-elute in an isocratic separation. The lowest value of amin obtained was 1.9 x 10-5 cm-1. The most significant advantage of the HPLC-BBCEAS study over previous studies arose from the recording of the absorption spectrum over a range of wavelengths. It was demonstrated that the spectral data collected could be represented as a contour plot which was useful in visualising analytes which nearly co-eluted. The LOD values for the two analytes studied indicated that the developed HPLC-BBCEAS setup was between 54 and 77 times more sensitive than a commercial HPLC system. For improved sensitivity and lower detection limits the low cost BBCEAS setup was used with a significantly longer 20 cm pathlength cell where the mirrors were in direct contact with the liquid phase analyte. This also reduced interface losses. The experiments were carried out using both R ³ 0.99 and R ³ 0.999 mirrors. The lowest αmin value obtained in this study was 2.8 x 10-7 cm-1 which is the lowest reported value to date for a liquid phase measurement, making this study the most sensitive liquid phase absorption measurement reported. The lowest LOD recorded was 4.6 pM, and was obtained for methylene blue with the R ³ 0.999 mirrors. A novel application of total luminescence spectroscopy to discriminate between different types of teas objectively was also investigated. A pattern recognition technique based on principal component analysis (PCA) was applied to the data collected and resulted in discrimination between both geographically similar and dissimilar teas. This work has shown the potential of fluorescence spectroscopy to distinguish between seven types of teas from Africa, India, Sri Lanka and Japan. Geographically similar black teas from 15 different plantation estates in Sri Lanka were also studied. The visualisation technique allowed the separation of all 11 types of teas when the first two principal components were utilised. The final part of the thesis describes the development of an optical sensor for the detection of ammonia gas. The operation of the sensor depended on the fluorescence quenching of the dye 9 amino acridine hydrochloride (9 AAH) immobilised in a sol gel matrix. It was also shown that the sensor response was not affected by the presence of acidic gases such as HCl and SO2. The final version of the sensor made use of dual channel monitoring to improve the sensitivity of the sensor. Measurements using diluted mixtures of ammonia gas in the range 5 -70 ppm showed that the response of the sensor was nonlinear, with the sensitivity increasing at lower concentrations. The measurement of the baseline noise allowed the LOD to be estimated at ~400 ppb.

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Pearce, E. I. "Analytical techniques for the study of soft contact lens spoilation." Thesis, Aston University, 1991. http://publications.aston.ac.uk/9761/.

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Soft contact lens wear has become a common phenomenon in recent times. The contact lens when placed in the eye rapidly undergoes change. A film of biological material builds up on and in the lens matrix. The long term wear characteristics of the lens ultimately depend on this process. With time distinct structures made up of biological material have been found to build up on the lens. A fuller understanding of this process and how it relates to the lens chemistry could lead to contact lenses that are better tolerated by the eye. The tear film is a complex biological fluid, it is this fluid that bathes the lens during wear. It is reasonable to suppose that it is material derived from this source that accumulates on the lens. To understand this phenomenon it was decided to investigate the make up and conformation of the protein species that are found on and in the lens. As inter individual variations in tear fluid composition have been found it is important to be able to study the proteins on a single lens. Many of the analytical techniques used in bio research are not suitable for this study because of the lack of sensitivity. Work with poly acrylamide electrophoresis showed the possibility of analyzing the proteins extracted from a single lens. The development of a biotin avidin electro-blot and an enzyme linked aniibody electro-blot, lead to the high sensitivity detection and identification of the proteins present. The extraction of proteins from a lens is always incomplete. A method that analyses the proteins in situ would be a great advancement. Fourier transform infra red microscopy was developed to a point where a thin section of a contact lens could yield information about the proteins present and their conformation. The three dimensional structure of the gross macroscopic structures termed white spots was investigated using confocal laser microscopy.

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Wangkarn, Sunanta. "Development of hyphenated analytical techniques for arsenic speciation in environmental and biological matrices." Thesis, Birkbeck (University of London), 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342227.

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Duford, David. "Instrumentation, fabrication techniques and method development for sample introduction, preparation and extraction on centrifugal microfluidic devices in motion." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110441.

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A growing number of pollutants are being shown to have a large environmental and health impact resulting in stricter legislative limits. Increased environmental monitoring is forcing analytical chemists to consider automating and miniaturizing current standard methods. Instrumentation and sample handling techniques for centrifugal microfluidic devices in motion have been developed with the objective of integrating multi-step reactions into a single device for the analysis of environmental solid samples.In order to study and optimize centrifugal microfluidic devices in motion, motorized stages integrating a camera, strobe and a variety of other peripheral components were developed. These allowed precise control of the devices throughout the methods' spin sequences and simultaneous acquisition of a series of stop action photographs of the devices.Non-contact methodologies for sample introduction, preparation and extraction on centrifugal microfluidic devices in motion are presented. To achieve this, hybrid fabrication techniques including the use of 3D printers were investigated and a World-to-Disk interface permitting the introduction of a solution gradient to a spinning device was developed. The interaction of integrated mobile magnets with a series of fixed magnets placed below the spinning devices was also investigated resulting in the development of both a magnetically actuated solid sample preparation and a magnetically actuated liquid-solid extraction technique. New automated and miniaturized methods for the analysis of environmentally important species such as polycyclic aromatic hydrocarbons and pesticides in solid samples are presented.
Les polluants ont des impacts importants sur la santé et l'environnement résultant à des restrictions accrues des limites législatives. Cette surveillance environnementale accrue pousse les chimistes analytiques vers l'automatisation et la miniaturisation des méthodes de référence actuelles. L'analyse d'échantillons environnementaux solides bénéficiera de cette envolée par le développement de nouveaux instruments et techniques de manipulation d'échantillon via des dispositifs microfluidiques centrifuges qui intègrent des réactions à étapes multiples sur un dispositif unique.Afin d'étudier et d'optimiser les dispositifs microfluidiques centrifuges en mouvement, des plateformes motorisées qui incluent une caméra, une lumière stroboscopique et une variété d'autres composantes périphériques ont été développées. Celles-ci ont permis le contrôle efficace des dispositifs tout au long des séquences giratoires et l'acquisition simultanée de séries de photographies en arrêt sur image.Des méthodologies sont présentées pour l'introduction, la préparation et l'extraction d'échantillons sur des dispositifs microfluidiques centrifuges en mouvement. Ceci fut réalisé grâce à la recherche de techniques de fabrication hybrides incluant l'utilisation d'imprimantes 3D menant au développement d'une interface permettant l'introduction de solutés à concentrations variables aux dispositifs en mouvement. De plus, l'interaction d'aimants mobiles intégrés avec une série d'aimants fixes placée sous les dispositifs en mouvement a mené au développement des techniques de préparation d'échantillons solides par force magnétique et d'extraction liquide-solide d'échantillons par force magnétique. De nouvelles méthodes automatisées et miniaturisées ont été développées pour l'analyse d'espèces environnementales importantes telles que les hydrocarbures polycycliques aromatisés et les pesticides dans des échantillons solides.

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Rybak, Michael E. "Development and application of thermal vaporization sample introduction techniques with demountable sample supports for inductively coupled plasma spectrometry." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37829.

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Novel approaches to thermal vaporization sample introduction for inductively coupled plasma (ICP) spectrometry using techniques with demountable sample supports are presented and compared. Developments and applications are presented for two sample introduction arrangements that use interchangeable sample probes in contact-free heating environments: direct sample insertion (DSI), and induction heating-electrothermal vaporization (IH-ETV). For the well-established technique of DSI, studies focused on the development and application of a pyrolytically coated graphite sample support, a feature common to conventional ETV systems. A process for coating sample probes in the ICP discharge was developed, and improvements were seen in both the reproducibility of the volatilization event and the appearance of the transient emission signals with ICP-optical emission spectrometry (OES) when a coated probe was used over an uncoated one. The pyrolytically coated sample probe was successfully used for the direct determination of several metals in wood pulps by ICP-OES, and was found not only to improve the appearance of the temporal signals, but also demonstrated a heightened resistance to chemical attack. For the prototypical IH-ETV system, a general study was first conducted to establish performance attributes and benchmarks such as heating characteristics, transport efficiency, and ICP-OES detection limits using several mixed carrier gases. The IH-ETV arrangement was found to be capable of rapid heating rates and precise, reproducible temperature control suitable for a thermal vaporization sample introduction technique. Of all the gas mixtures studied, the incorporation of 15% (v/v) SF6 into the Ar carrier flow resulted in the best overall conditions for the vaporization, transport and detection of analytes by ICP-OES. These conditions were successfully used for the determination of various metals in soil and sediment samples by ICP-OES using IH-ETV sample introduction. Addit

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Li, Linlin. "Microstructure characterization of polymers by modern NMR techniques." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1353000762.

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Najafi, Ali. "Application of Polymeric Ionic Liquid Solid-Phase Microextraction Sorbent Coatings and Ionic Liquid Stationary Phases for Liquid and Multidimensional Gas Chromatographic Techniques." University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1449846148.

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Samskog, Jenny. "Development of Micro Liquid Separation Techniques using Electrospray Ionisation Mass Spectrometry in the Analysis of Polar Compounds and Proteins/Peptides." Doctoral thesis, Uppsala University, Analytical Chemistry, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3304.

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Electrospray ionisation (ESI) coupled to mass spectrometry (MS) is one of the most important detection techniques for chemical analysis of small drugs as well as large biomolecules in life science today. In this thesis, aspects on improved compatibility between liquid based separation systems and mass spectrometric detection were investigated regarding buffers, sample preparation and analysis of polar compounds as well as peptides and protein digests for enhanced ESI-MS performance.

Capillary electrophoresis (CE) coupled to ESI-MS detection, was evaluated using both a sheath flow interface and a sheathless design. The separation of peptides and small, polar compounds was optimised for both CE-ESI interfaces. The effect of sheath liquid composition was also studied with the aim to improve sensitivity in the ESI-MS detection.

Polar compounds were retained and separated by capillary ion-pair chromatography coupled to ESI-MS detection. Since commonly used ion-pairing reagents are detrimental to the ESI process they were effectively removed before the ionisation by the use of a trapping column after the separation. Alternatively, the ion-pairing reagents were exchanged to volatile constituents.

A method for peptide mapping by liquid chromatography (LC)-ESI-MS was developed for lactate dehydrogenase. The method was further enhanced to involve the proteolysis on-line to the LC-ESI-MS. No manual sample handling was then needed and the total analysis time decreased from 7 to 1.5 hours. The amount of information was also shown to increase in the on-line system.

Finally, the on-line concept was extended to an innovative interface for direct coupling of a pumped liquid flow to an electroosmotically driven flow. This provided a valve-free sample transfer between capillary LC and CE, aiming towards increased peak capacity per unit time for the analysis of complex peptide samples.

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Amirkhani, Ardeshir. "Development of Techniques and Methods for the Quantitative Analysis of Endogenous Substances by Microcolumn Liquid Chromatography Coupled to Mass Spectrometry." Doctoral thesis, Uppsala University, Analytical Chemistry, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3990.

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Liquid chromatography-mass spectrometry (LC-MS) is a powerful technique for the analysis of endogenous compounds. The introduction of electrospray ionization (ESI) as an interface between LC and MS has contributed strongly to a trend towards miniaturization of LC, due to the possibility to perform ESI at low flow rates. In this thesis, several aspects regarding the design of miniaturized LC systems and electrospray emitters were investigated. In addition miniaturized LC-ESI-MS have been used for the qualitative and quantitative analysis of endogenous polar compounds, peptides and protein digests.

The performance of miniaturized LC-MS was compared using different electrospray emitter configurations. The results indicated that the efficiency of the LC system is rather independent of the configuration of the emitter.

The lifetime of gold-coated fused silica electrospray emitters based on vapor deposited adhesion layers of titanium were investigated. The long lifetime of the emitter facilitates the use in LC-MS experiments, exemplified LC-MS by analysis of neuropeptides.

The ESI voltage is shown to interfere with liquid chromatographic separations performed in packed porous graphitic carbon capillary column. This interference is ascribed to the presence of an electric field over the conductive column in absence of a ground point between the column and the ESI emitter.

The solid supported enhanced microdialysis for analysis of neuropeptides were compared with conventional microdialysis. The difference between the two methodologies were evaluated by LC-MS analysis of the microdialysates. The solid supported method gave in general higher relative recoveries.

Finally, a method of standard addition was developed to determine total level of tryptophan and two of its metabolites in human plasma by capillary LC-ESI tandem mass spectrometry. The method was applied in a clinical study of multiple scleroses patients treated with cytokines (IFN Beta 1a, 1b). The results show that the intervention effects the tryptophan metabolism.

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Cáceres, Ana B. "The development of methods for the determination of selenium using spectrofluorimetric and ICP-MS techniques." Thesis, Sheffield Hallam University, 2002. http://shura.shu.ac.uk/19425/.

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Methods for both the on-line and off-line fluorimetric determination of total selenium and selenium species using 2-(alpha-pyridyl)-thioquinaldinamide (PTQA) as a fluorimetric reagent have been developed. As PTQA is not available on the market, methods for its synthesis were critically reviewed, and in the light of the information obtained, modifications were made to the synthesis and purification conditions in order to improve yield from 16 % to 38.9 %. The synthesised PTQA was used for the optimisation of a batch fluorimetric method based on the reaction between the reagent and Se (IV) in acidic medium. The developed method was applied to the determination of total selenium in nutritional supplements after microwave digestion and photoreduction of Se (VI) to Se (IV). The analytical precision in the concentration range 0. 5 - 1000 mug ml[-1] was better than 5%. Excellent agreement (r[2] = 0.9960) between the results of the fluorimetric and ICP-MS methods was obtained when a reference material, TMDA 51.2 supplied by National Water Research Institute Environment Canada and three nutritional supplements were analysed. A novel automated fluorimetric method for the simultaneous determination of Se (VI) and Se (IV) is described in which a purpose built flow injection system was used for the on-line photoreduction of Se (VI) to Se (IV) before detection. Variables such as tube diameter, flow rates, type of acids (HNO[3], H[2]SO[4], CH[3]COOH, H[3]PO[4] and HCI) that affect the rate at which PTQA reacted with Se (IV) were investigated and optimised. The linear calibration range was found to depend on the type and concentration of acid. The most intense fluorescence signals were observed in HNO3 and at a PTQA concentration of 5x10[-4] M. A sample throughput of 8 samples/hr was achieved. Method validation was by comparing the results obtained for the determination of selenium in nutritional supplements with those from ICP-MS.Selenium speciation in the nutritional supplements was studied using a developed method in which the selenium species selenomethionine, Se (IV), and Se (VI) were extracted, separated by HPLC prior to on-line photoreduction of Se (VI), and post column hydride generation before ICP-MS detection. Separation of the three species was achieved with excellent resolution in less than 18 minutes. The limit of determination for the three species was 0.50 mug L[-1].

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Combs, J. Dale. "Study of a Model alpha-Helix Peptide's Surface Properties by Langmuir Monolayer Techniques and Surface FTIR." Thesis, Middle Tennessee State University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10146886.

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Cell membranes have been shown to be able to change the conformation of proteins/peptides. However, the structure of the cell membrane is complicated and has been divided to three regions: the hydrophobic region containing alkyl chains, the hydrophilic head group, and the hydration layer, or lipid-water interface, which exists between the hydrophilic head group and the bulk water solution, but with lower dielectric constant compared with fully hydrated water. The air-water interface has been used to mimic the structure of the hydration layer because of their similar dielectric constant.1,2 Some proteins were found to form a stable Langmuir monolayer and accumulate at the air-water interface. For example, ?-synclein, a membrane protein containing 140 amino acids, is unstructured in aqueous solution but changes its conformation to α-helix at the air-water interface. This incites interest to investigate short motifs of α-helix to form a stable Langmuir monolayer at the air-water interface. In this thesis, a peptide with sequence of YAAAA(KAAAA)4 (referred as Pep25 hereafter) was used as a model peptide of α-helix to spread at the air-water interface, because our group has determined the conformation of Pep25 in residue level by the 13C isotope-edited FTIR. Langmuir monolayer technique together with IRRAS showed that Pep25 does not form a typical Langmuir monolayer at the interface. Potential plans to make Pep25 to form a stable monolayer are also discussed in this thesis.

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Bonn, Jonas. "Improved Techniques for Sampling and Sample Introduction in Gas Chromatography." Licentiate thesis, KTH, Chemistry, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4744.

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Sampling and sample introduction are two key steps in quantitative gas chromatography. In this thesis, a development of a previously described sampling technique as well as a novel concept for sample introduction in gas chromatography are presented. The thesis is based on two papers.

Paper I describes a method for preparing physically mixed polymers for use as sorbent phases in open tubular trapping of gaseous analytes. The concept is based on mechanical disintegration and mixing of solid or liquid poly(ethylene glycol), PEG, into poly(dimethylsiloxane), PDMS, in a straightforward manner. The resulting mixture exhibits a higher affinity towards polar analytes, as compared to pure PDMS.

Paper II describes a novel approach to liquid sample introduction with the split/splitless inlet, used in gas chromatography. Classical injection techniques struggle with discrimination of high boiling analytes and poor repeatability of the injected amount of analytes. The presented injection technique utilizes high voltage to obtain a spraying effect of the injected liquid. The spraying effect can be achieved with a cold needle, which is unprecedented for gas chromatographic injections. The cold needle spraying results in highly repeatable injections, free from discrimination of high boiling analytes.

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JAYASINGHE, SARATH B. "INVESTIGATION OF SELENOPROTEOME AND METALLOPROTEOME OF SEEDS OF BERTHOLLETIA EXCELSA AND METALLOPROTEOME OF SEEDS OF GLYCINE MAX BY LC AND MS TECHNIQUES." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1196265688.

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28

Sheridan, Kevin Thomas. "Experimental techniques for cold chemistry and molecular spectroscopy in an ion trap." Thesis, University of Sussex, 2013. http://sro.sussex.ac.uk/id/eprint/47145/.

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A range of experimental techniques for application in reaction studies between ionic and neutral atoms/molecules and high resolution spectroscopy experiments with sympathetically cooled molecular ions are presented. A novel ion trap loading scheme using the photo-ionisation of atoms generated by the pulsed laser ablation of a solid calcium target has been characterised. We have identified the range of ablation laser fluences that must be used in order to produce a flux of neutral calcium atoms, which is a prerequisite for isotope selective ion trap loading. Calcium ions are trapped and laser cooled in a linear radio-frequency ion trap. We have developed a spectroscopy scheme that allows the entire fluorescence spectrum of trapped ions to be rapidly collected with high precision while maintaining a low ion temperature and good ion localisation throughout interrogation. The scheme has been demonstrated by measuring the saturation intensity of the calcium ion 4S1/2→4P1/2 transition. We have developed a novel scheme to measure the secular motion of trapped ions and demonstrated the application of the technique to ion-neutral collision reaction experiments. Employing pulsed excitation and Doppler velocimetry, we have measured the centre-of-mass mode frequency of single ions as well as large ion crystals with a frequency precision better than 2x10-3 within an interrogation time on the order of seconds. This method has been used to measure the mass of ions and observe charge exchange collisions between trapped calcium isotopes. In particular, we have measured the 44Ca++40Ca!40Ca++44Ca reaction cross section and demonstrated the single-event resolution of the technique. Finally, we have developed a novel all-optical broadband scheme for exciting, amplifying and measuring the secular motion of ions in the trap. Oscillation induced by optical excitation has been coherently amplified to control and measure the ion's secular motion. Requiring only a single interrogation laser, the ion's oscillation amplitude can be precisely controlled. The application of this technique to non-destructive spectroscopy of trapped molecular ions is discussed.

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Hernandez, Pedro Wilfredo Araujo. "Applications of experimental design and calibration in analytical chemistry and improved chlorophyll measurement techniques." Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389305.

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Danziger, James Lee. "Characterization of molecular semiconductor and multilayer molecular organic photoconductor interfaces by photoelectrochemistry and surface analytical techniques." Diss., The University of Arizona, 1990. http://hdl.handle.net/10150/185217.

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Organic semiconductor thin films are of interest to us for a variety of molecular electronic applications, including solar cells, chemical sensors, and nonlinear optical devices. We have been seeking unusual new ways of controlling the composition and long-range molecular structure of these materials through the use of vacuum deposition techniques which mimic, in some ways, those used for epitaxial layer growth in inorganic materials. Thin films of perylene tetracarboxylic dianhydride (PTCDA) have been examined as electrodes and photoelectrodes on both metal and metal oxide substrates. In contrast to most previous studies of phthalocyanine thin films, these materials behaved in such a way as to suggest n-type character, i.e. dark electron transfer reactions were facile in negative potential regions with solution redox couples, and little dark electrochemistry could be observed in regions of positive potentials. It is likely that junction formation occurs only as a result of illumination, with different rates of interfacial hole and electron injection and transport, at the PTCDA/electrolyte interface. Electron microscopy of the PTCDA films indicated that they were deposited as elongated crystallites, with relatively large spaces between individual crystallites, which strongly affected their dark and photoelectrochemical behavior, especially on Au substrates. Electrochemical polymerization of α-napthol was carried out to passivate sites that were electrochemically active in the dark, a treatment which greatly enhanced the overall electrochemical activity of these PTCDA thin films. A variety of p-n heterojunction-like structures, created from thin film molecular materials (vanadyl phthalocyanine (VOPc) and perylene tetra-carboxylic dianhydride (PTCDA)), have been nondestructively explored by photoelectrochemical techniques and UHV surface analytical techniques. Vacuum deposited bilayers and multilayers of these thin films behave like "p-n" diodes over a narrow potential window. The open circuit photopotential is determined by the junction potential formed at the Pc/PTCDA interface. It was found that the transient photocurrent (using a modulated light source) in multilayer VOPc/PTCDA assemblies was directly related to the number of interfaces present, consistent with the idea that exciton dissociation is localized primarily to such an interface, and is the photocurrent limiting process.

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Liti, Samone. "Evaluation of sample preparation techniques for MALDI-TOF-MS analysis of oligosaccharides." Thesis, Uppsala universitet, Avdelningen för analytisk farmaceutisk kemi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-277957.

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The aim of this study was to optimize the sample preparation and methods for analysis of oligosaccharides of hyaluronic acid with MALDI- TOF-MS. The analysis was carried out on an Autoflex speed MADLI-TOF- MS instrument with both linear and reflectron mode. Matrices used in this study were 2,5-DHB and Super-DHB and type of matrix was chosen depending on the size of the analyzed oligosaccharides. The application of sample and matrix on the target that gave the most homogenous crystallization was sandwich and the laser power in the MALDI was kept at 65 %. Since it is known that salts and buffers interfere with the analysis, sample clean-up such as solid phase extraction (SPE) in pipette tips and dialysis was performed. SPE worked best for low mass oligosaccharides and provided high intensity and little noise. With SPE a concentration of the analyte could be done which was the advantage over dialysis. Dialysis worked well for larger oligosaccharides and mixtures of different sized oligosaccharides. Another way of using MALDI for biomolecule analysis is with TLC-MALDI. A fast and accurate separation was achieved and analysis could be done directly from the plate. The optimized methods were evaluated according to linearity and precision, LOD, mass accuracy and matrix stability. The linearity and precision was good in a higher concentration range (50 μg/mL and higher), but the test for limit-of-detection (LOD) indicated that concentrations from 20-30 μg/mL could be analyzed with no interference from the background. The mass accuracy was within the acceptable limits according to Bruker Daltonics when a mass calibration was done for each analyzed sample. The stability of the matrix in solution was difficult to study because of the day-to-day variation in intensities given by the MALDI-TOF-MS technique.

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Shah, Syeda Amena Batool. "Method development and application of novel analytical techniques for determining illicit and therapeutic drug use." Thesis, Kingston University, 2014. http://eprints.kingston.ac.uk/32207/.

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The research described in this thesis is based on novel analytical approaches to develop new methods for determining psychoactive and therapeutic drugs in biological matrices. All the analytical methods developed were according to Food and Drug Administration (FDA) guidelines. The first project involved development and validation of an analytical method for quantification of psychoactive drug mephedrone and its two metabolites 4- methylephedrine and 4-methylnorephedrine in human hair using liquid chromatography tandem mass spectrometry (LC-MS/MS). Recent abuse of designer drugs such as mephedrone has presented a requirement for sensitive, reliable and reproducible analytical methods for the detection of these controlled drugs in different matrices. Based on the similar structure of mephedrone to other methcathinones and amphetamines, the study also proposed a similar metabolic pathway for mephedrone. The method developed can be of great value for the future detection of mephedrone and its two metabolites in human hair. Having completed the above, another analytical method was developed capable of detecting 0.6 ng/mg abacavir and tenofovir in human hair using LC-MS/MS. The method was successfully validated for the intraday precision, interday precision, and limit of detection, accuracy and extraction recovery. This is the first full report of a method for the simultaneous determination of these two key antiretroviral drugs in hair. The newly developed method is useful for future routine analysis of tenofovir and abacavir in human hair and could be used in therapeutic drug monitoring and adherence to medicines studies, which would be helpful in decision making regarding treatment change in combination anti-retroviral therapies. The last project focused on analysing dietary substances such as green and white tea, fruit juices along with catechins present in tea and corticosteroids in order to investigate potential inhibitory effects on the glucuronidation of B2" agonists clenbuterol and formoterol. [3;- agonists are frequently prescribed for the treatment of asthma in athletes. Due to performance-enhancing effects, these [3;- agonists have been subjected to restrictions in sport. A glucuronidation method using human liver microsomes (HLM) and uridine 5'-diphospho-glucuronosyltransferase (UGT2B17) has been used. The study shows that common dietary products and the catechins present in tea inhibit the glucuronidation activity of forrnoterol which effects/alters the actual drug concentration when testing in human body/urine and may help in masking formoterol misuse therefore having implications on current doping control in sport.

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Khoj, Manal A. "Investigation of solid materials and their transformation processes by X-ray and complementary analytical techniques." Thesis, Cardiff University, 2016. http://orca.cf.ac.uk/98351/.

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The work presented in this thesis concerns the investigation of a family of cinnamic acid derivatives. A combination of complementary analytical techniques is used to explore detailed structural aspects, and subsequently, chemical and physical properties of some of the materials. The crystal structures of the materials have been determined by single crystal X-ray diffraction techniques. Chapter 1 reviews the relevant background knowledge including crystal engineering aspects and supramolecular chemistry, intermolecular interaction, polymorphism in crystalline materials, solid state processes such as phase transformation and solid state photoreaction, cocrystallization, and the mechanogrinding approach. Chapter 2 provides background information relating to the main experimental techniques employed in this work. These include single crystal X-ray diffraction, powder X-ray diffraction, thermal analysis (deferential scanning calorimetry) and high performance liquid chromatography. Chapter 3 explores the polymorphism of meta-substituted-cinnamic acids and phase transformation between related polymorphs, resulting in the discovery of two rare cases of transformation of cinnamic acids, in which the two forms of the same polymorphic classification. Chapter 4 investigates the feasibility of the cocrystallization of binary systems that contain the different cinnamic acids studied in Chapter 3, resulting in the discovery and characterization of several crystal structures of different binary systems. The binary systems investigated by a combination of thermal analysis and PXRD, revealing information on the effect of the components on the obtained structure. Chapter 5 investigates the structural aspects of K+ and NH+ salts of the different cinnamic acids investigated in Chapter 3. The study extended to explore the feasibility of cocrystallization of different binary salts systems (bi-anion or bi-cation salts), resulting in the design of materials that undergo photodimerization reaction. The study also provides considerable information on the effect of the substituents and the cations on the structure obtained. Chapter 6 gives evidence of the occurrence of the photodimerization process in several solid systems (investigated in previous chapters) in which the structures showed optimal arrangement of the double bond. The work also includes the reaction occurring in some binary solid solution systems, revealing a random molecular distribution of molecules throughout the reactant crystalline materials. The study also investigates the photoreaction in systems exhibiting a criss-cross arrangement of the double bonds, providing information on the dimerization and oligomerization of the materials. Chapter 7 reports interesting insights into the green chemistry approach of mechanogrinding and solvent drop grinding of a system contains 3-BrCA and 3-ClCA. Cocrystallization and the phase control is achieved via the process. Chapter 8 gives an overview on the future work.

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Vuppalapati, Ragini. "Chemical Modification on Gold Slides to Gain Better Control of Patterning Techniques." TopSCHOLAR®, 2011. http://digitalcommons.wku.edu/theses/1129.

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Nanolithography is a rapidly evolving field that requires new combinations of techniques to improve patterning and to assist in fabricating electromechanical devices. An increasing number of applications require surfaces with defined regions of different chemical functionality. In our previous project optimum conditions for lithographic patterning were determined and potential blockers were identified to reduce force on the tip. This work is focused on identifying good chemical modifications that will allow better control of basic patterning and to investigate the minimum force of patterning required while using each chemical system. The primary aim is to gain better control of basic pattern techniques in order to create more intricate patterns such as interdigitated arrays, which can subsequently be used in sensors. An atomic force microscope (AFM) is used to pattern the prepared colloid-coated glass slides. Several compounds were used in the investigation, including sodium sulphate, potassium sulphate, magnesium sulphate, sodium fluoride, sodium chloride, sodium bromide, and sodium iodide, potassium chloride, potassium bromide, potassium iodide, potassium dihydrogen phosphate, and potassium hydrogen phosphate. In Summary, the following were found as a result of this work:  The groups of sulphates were determined to require minimum patterning forces as indicated. Sodium sulphate took a force of 49 n Potassium sulphate took a force of 45 nN Magnesium sulphate took a force of 744.4 nN  The group of sodium and potassium halides were determined the minimum patterning forces as indicated. Sodium fluoride took a force of 8.42 nN Sodium chloride and potassium chloride took a force of 20.19 and 61.9nN Sodium bromide and potassium bromide took a force of 601.4 nN and 37.2 nN, respectively Sodium iodide and potassium iodide took a force of 953.7 nN and 47.2 nN, respectively  The phosphates were determined to require the minimum patterning forces as indicated. Potassium hydrogen phosphate took a force of 25nN Potassium dihydrogen phosphate took a force of 43 nN

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Stanley, Floyd E. III. "Advancing Modern Forensic Investigations Through The Use of Various Analytical Techniques." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1321372527.

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Magalhães, Luís Miguel Andrade de. "Developement of Automatic Methods Based on Flow Techniques for Evaluation of Antioxidant Capacity in Pharmaceutical and Food Products." Doctoral thesis, Faculdade de Farmácia da Universidade do Porto, 2007. http://hdl.handle.net/10216/7428.

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Magalhães, Luís Miguel Andrade de. "Developement of Automatic Methods Based on Flow Techniques for Evaluation of Antioxidant Capacity in Pharmaceutical and Food Products." Tese, Faculdade de Farmácia da Universidade do Porto, 2007. http://hdl.handle.net/10216/7428.

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Huynh, Vivian. "Forensic Analysis of Ink on Documents Using Direct Analyte-Probed Nanoextraction Coupled Techniques." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849635/.

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Analzying questioned documents in a nondestructive nature has been an issue for the forensic science community. Using nondestructive techniques such as video spectral comparator does not give reliable information due to the variations in gray or color levels that are distinguished differently by analysts. Destructive techniques such as chromatography give dependable, qualitative and quantitative, information but involves altering the evidentiary value of these questioned documents. The paradox of document examination becomes a problem when document evidence is involved, especially when trying to preserve its evidentiary value and critical data is needed. Thus, a nondestructive technique has been developed to solve the loopholes in document examinations. Direct analyte-probed nanoextraction (DAPNe) is a nanomanipulation technique that extracts ink directly off the document for further examination. A watermark is left, at most, post-extraction. DAPNe utilizes a tip emitter, pre-filled with a solvent, which is controlled in x-, y-, and z-coordinates via joystick controller and aspirates/extracts using a pressure injector. The versatility of this technique lies within the solvent chemistry and its capability to be coupled to various types of instrumentation. The extraction solvent can be altered to target specific components in the ink. For example, a chelator may be added to target metal ions found in ancient inks or methanol may be added to target certain organic resins and binding agents found in modern inks. In this study, DAPNe has been coupled to nanospray ionization mass spectrometry, fluorescence microscopy, Raman spectroscopy, matrix-assisted laser desorption ionization mass spectrometry, and laser ablation to solve questioned document concerns in the area of falsified or forged documents, redacted documents, and aging studies.

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Lenart, William R. "EXPANDING EXPERIMENTAL AND ANALYTICAL TECHNIQUES FOR THE CHARACTERIZATION OF MACROMOLECULAR STRUCTURES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1584358701735061.

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40

Chari, Sangeetha. "Hydride Generation and Laser Spectroscopy Techniques for Trace Analytical Measurements of Antimony and Selenium." Connect to resource online, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1219424557.

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41

Gamez, Gerardo. "Advances in analytical spectrochemistry with ionized gases. I. Improved fundamental understanding through laser based techniques. II. Novel bioanalytical applications." [Bloomington, Ind.] : Indiana University, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3223049.

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Thesis (Ph. D.)--Indiana University, Dept. of Chemistry, 2006.
"Title from dissertation home page (viewed June 28, 2007)." Source: Dissertation Abstracts International, Volume: 67-06, Section: B, page: 3105. Adviser: Gary M. Hieftje.

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42

Chen, Siying. "Characterization of crystalline and solution-processable phthalocyanine assemblies by electrochemical, photoelectrochemical, and surface spectroscopic techniques." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282120.

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Ultrathin organized films of organic electronic materials, such as phthalocyanines (Pc), are promising for both fundamental and applied studies due to their special optical, electronic and photoconductive properties. The studies presented in this dissertation include fabrication of ultrathin molecular assemblies by molecular beam epitaxy and Langmuir-Blodgett techniques. The degree of molecular order, extent of charge transfer and the morphology within these films, assessed by methodologies, such as photoelectrochemistry, electrochemistry, surface analysis and optical spectroscopy were discussed and characterized. Under high vacuum condition, a wide range of ordered structures of some trivalent metal phthalocyanines, such as GaPc-Cl, InPc-Cl and AlPc-F, can be fabricated. These materials exhibit "layer-by-layer" growth on the single crystal SnS₂ surface when deposited by molecular beam epitaxy (MBE). The MBE technique allows for closer packing of these highly ordered phthalocyanines than in self-assembled (SA) or Langmuir-Blodgett (LB) thin films, due to the lack of hydrocarbon side chains which are necessary for control of molecular architecture during SA or LB depositions. Several new solution processable substituted phthalocyanines are introduced, which due to their strong self-assembled tendency, may be suitable for the formation of well organized thin films by SA and LB techniques. It is found that the types of the substituents attached to the Pc rings play a significant role in determining both the aggregation tendency and the electrochemical properties of Pcs. Surface pressure-area isotherms of these substituted phthalocyanines show that there can be one or two stable phase transition regimes for monomolecular film at the air/water interface. On-trough spectroscopic studies of benzylalkoxy substituted phthalocyanines show that in the pressure-area region prior to the formation of the first stable phase extensive aggregation has occurred. Electrochemical studies of fully compressed films of substituted phthalocyanines on certain substrates show the presence of multiple electroactive domains, controlling the oxidation or reduction process of the Pc rings. Spectroelectrochemical studies of LB films of CuPcOC₂OBz suggest that the presence of both monomer and aggregates leads to the two separate oxidation processes.

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De, Villiers A. J. (Andre Joubert). "Application of modern analytical techniques and chemometric methods to the chemical characterisation of South African wines : determination of non-volatiles." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/49850.

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Thesis (PhD)--Stellenbosch University, 2004.
ENGLISH ABSTRACT: The present study deals in the first instance with the improvement of current analytical techniques for the analysis of the non-volatile content of wines. An improved sample preparation method, using solid phase extraction (SPE), was initially developed for the analysis of organic acids, sugars and phenolic compounds. Consequently, modem analytical methodologies were assessed to obtain optimal techniques for the separation of various non-volatile compounds. A capillary electrophoresis (CE) method, demonstrably more reliable than currently used high performance liquid chromatography (HPLC) and CE methods, is proposed for the analysis of organic acids. HPLC with refractive index (RI) or evaporative light scattering detection (ELSD) proved more suitable than CE for the analysis of sugars in dry wines. Liquid-chromatography-mass spectroscopy (LC-MS) offered superior sensitivity and resolution compared to the relatively new technique of CE-MS for the analysis of wine phenolics. LC-MS was further applied for the efficient and sensitive analysis of non-coloured phenolics and anthocyanins in wine. Negative- and positive electrospray ionisation, respectively, were used in conjunction with an ion-trap mass analyzer, for the identification of 34 phenolics and 31 anthocyanins in red wine samples. Complementary CE and LC methods were developed to allow the identification of artificial dyes in red wines, added illegally to improve their colour. Also, the application of stir bar sorptive extraction (SBSE) with liquid desorption and micellar electrokinetic chromatography (MEKC) for the analysis of bitter acids in beer is reported. In the second part of the thesis, the analytical results obtained for South African red and white wines were evaluated. Following comparison of the results with literature reports, several pattern recognition techniques were employed. A classification function obtained by linear discriminant analysis (LDA) was used to classify both red and white wines according to variety, based on their chemical composition. This classification is achieved independent of the factors of wine age or geographical origin, making it useful for authenticity evaluation.
AFRIKAANSE OPSOMMING: Hierdie studie het as primêre doel die verbetering van bestaande analitiese metodes vir die analise van nie-vlugtige komponente in wyn. In die lig hiervan, is eerstens 'n toepaslike monster-voorbereidingstegniek, gebasseer op soliede fase ekstraksie (SPE), ontwikkel vir die gelyktydige analise van organise sure, suikers en fenoliese komponente vanuit die wyn matriks. Vervolgens is moderne analitiese rtietodes ondersoek en gepastde skeidingstegnieke is ontwikkel vir die verskillende chemiese wyn-komponente. Kappillêre elektroforese (CE) en hoë-druk vloeistof-chromatografie (HPLC) in kombinasie met verskeie deteksie-metodes is vergelyk. Hieruit is 'n verbeterde CE metode vir die analise van organise sure is ontwikkel, terwyl HPLC in kombinasie met refraksie-indeks- en verdampings lig verstrooiings deteksie (ELSD) die beste resultate lewer vir die analise van suikers in droë wyne. Die toepasbaarheid van vloeistof-chromatografie met massa spektrometriese deteksie (LC-MS) vir die analise van fenoliese komponente is gedemonstreer, terwyl CE-MS onvoldoende resolusie en sensitiwiteit toon vir die analises. LC-MS is vervolgens ook gebruik vir die identifikasie van 34 fenoliese verbindings en 31 antosianiede in rooi wyn. Komplementêre HPLC en CE metodes is ontwikkel vir die identifikasie van onwettige sintetiese kleurstowwe in' rooi wyn. 'n Addisionele monstervoorbereidingsstap, roerstaaf sorptiewe ekstraksie (SBSE), is saam met vloeistof-desorpsie en misellêre elektrokinetiese chromatografie (MEKC) gebruik vir die analise van hops bitter sure in bier. In die tweede deel van die tesis word die resultate verkry m.b.v. bg. tegnieke vir die analise van Suid-Afrikaanse rooi- en wit wyne, bespreek. Die resultate is vergelyk met waardes uit die literatuur, en verskeie statistiese metodes is gebruik om die data te ondersoek. Met behulp van chemometriese metodes is 'n klassifikasie funksie verkry wat die klassifikasie van Suid-Afrikaanse wyne volgens druifsoort, gebasseer op die chemiese samestelling van die wyne, toelaat. Die klassifikasie is moontlik, onafhanklik van die ouderdom of geografiese oorsprong van die wyne.

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Dixon, Daniel Wayne. "Characterization of Commercial Pectin Preparations by Spectroscopic and Chromatographic Techniques." Digital Commons @ East Tennessee State University, 2008. https://dc.etsu.edu/etd/1910.

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Pectin has a long history as a food additive. However, elucidation of its fine structural and property relationships remains elusive. Recent research has focused on pectin's ability to complex with divalent heavy metals to aid in characterizing it. Commercial pectins of unknown composition were obtained from local grocers. Purified pectin samples from orange peel, lemon peel, and apple pomace, each of low and high levels of methyl esterification and of unknown distribution pattern were also purchased. Instead of metal complexation, several highly absorbing dyes such as Ruthenium Red, Nile Blue, and Acridine Orange were used to complex with the pectins and their resulting UV-Vis spectral patterns were employed to determine if one can characterize the different pectins. Chemometric methods are also included to aid in distinguishing them apart.

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45

DeNicola, Cafferky Katie. "ASSESSMENT OF METAL CONCENTRATIONS AND SPECIES IN BIOLOGICALLY RELEVANT SAMPLES WITH INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRIC TECHNIQUES." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1155754956.

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46

Casiano-Maldonado, Madalis. "Mass Spectrometry Techniques for the Characterization of Synthetic Polymers, Biopolymers, Biodegradation Products and Their Interactions." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1332962590.

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47

Wahlen, Raimund. "Development of analytical techniques for the extraction, separation and determination of organometallic and inorganic metal species in environmental and biological matrices." Thesis, Kingston University, 2003. http://eprints.kingston.ac.uk/20722/.

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Existing methodologies for the separation and detection of organotin species by liquid- and gas-chromatography coupled to inductively coupled plasma mass-spectrometry (ICP-MS) have been improved significantly. The LC separation of dibutyltin (DBT), triphenyltin (TPhT) and unidentified species in mussel tissue has been enhanced in terms of peak shape and resolution. GC-ICP-MS detection limits for organotin species are significantly reduced by addition of oxygen or nitrogen to the ICP-MS carrier gas. A comparison of LC-ICP-MS and GC-ICP-MS for the species-specific isotope dilution determination of tributyltin (TBT) in sediment extracts has shown that both methods deliver accurate results. However, GC-ICP-MS is significantly more sensitive (absolute detection limit of 0.03 pg TBT as Sn compared to 3 pg TBT as Sn by LC-ICP-MS) and provides superior isotope ratio measurement precision, which is linked to more reproducible peak integration and greater analyte signals by this technique. [sup]117Sn enriched DBT and TBT have been used to investigate the stability of species during extraction and the derivatisation efficiency of ethylation. The speciation of arsenic (As) has been performed using anion-exchange chromatography coupled to ICP-MS detection. Good separations have been achieved for up to seven species including monomethyl- and dimethylarsinic acid (MMA and DMA) and especially between arsenobetaine (AsB) and arsenite (As(III)). The accuracy and precision of the methods have been tested by analysis of a range of biological certified reference materials. Extraction methods for organotin and arsenic species have been developed using accelerated solvent extraction (ASE), and this technique has been assessed for the simultaneous co-extraction of Sn, As and Hg species from environmental samples. Accurate data were obtained for DBT, TBT, AsB and DMA in a certified oyster tissue, and promising results were also obtained for methylmercury. The combined extraction, separation and detection methods have been used to determine the vertical profiles of organotin and arsenic species in sediments from the Thames estuary (UK). Vp to nine organotin species were detected, with DBT being the predominant at levels ranging from [tilde] 12 - 160 ng/g (as Sn). The main As species were As(III) and As(V) at concentrations between [tilde] 160 - 4200 ng/g (as As). Methylated arsenicals were also detected throughout the core.

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Altun, Zeki. "New Techniques for Sample Preparation in Analytical Chemistry : Microextraction in Packed Syringe (MEPS) and Methacrylate Based Monolithic Pipette Tips." Doctoral thesis, Karlstad : Faculty of Technology and Science, Chemistry, Karlstad University, 2008. http://www.diva-portal.org/kau/abstract.xsql?dbid=1420.

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Viberg, Pernilla. "Development of non-adherent single cell culturing and analysis techniques on microfluidic devices." Diss., Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1441.

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Bell, Benjamin. "Advancing the application of analytical techniques in the biological chemistry of sporopollenin : towards novel plant physiological tracers in Quaternary palynology." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/advancing-the-application-of-analytical-techniques-in-the-biological-chemistry-of-sporopollenin-towards-novel-plant-physiological-tracers-in-quaternary-palynology(59605f2b-642a-4ea9-8921-4c926217e6f2).html.

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Palynology, the study of organic microfossils, is an important tool for improving our understanding of past environments and landscapes. Palynology provides a wealth of information from which climatic and environmental conditions can be inferred. However, inferred climatic and environmental conditions are often open to interpretation. Assumptions made about past climate conditions from pollen assemblages often rely on qualitative understanding of modern-day vegetation distributions, rather than empirical relationships. Historic anthropogenic impact on the environment must also be inferred, and assessments made as to whether vegetation changes are a result of climate change or human impact. This study seeks to address some of the questions that arise through the interpretation of pollen assemblages, by establishing empirical relationships between the geochemistry of modern pollen and climate or environmental controls. It focuses on the pollen of the climatically sensitive montane conifer Cedrus atlantica, which is distributed across the mountains of Morocco and Algeria. The study investigates aspects of modern pollen geochemistry and morphology and finds a strong relationship between the stable carbon isotope composition of modern pollen and mean annual precipitation (r2 = 0.54, p <0.001) and summer precipitation (r2 = 0.63, p <0.0001). Furthermore, a stronger relationship exists with aridity measured using the self-calibrating Palmer Drought Severity Index (r2 = 0.86, p <0.0001), suggesting that the stable carbon isotope composition of Cedrus atlantica pollen is influenced by environmental moisture availability. The study also finds there is an increased abundance of ultraviolet absorbing compounds (UACs) in modern Cedrus atlantica pollen with increasing summer UV-B flux. This relationship was evident with samples growing in their native range (r2 = 0.84, p <0.0001), but not with samples from outside this range (r2 = 0.00, p = 0.99), suggesting a possible genetic influence. Lastly, the study finds that grain size of Cedrus atlantica pollen is highly variable within and between samples, and we rule out climatic control on pollen grain size. These results suggest that quantitative relationships can be established between the geochemistry of Cedrus atlantica pollen and environmental and climatic influences. Stable carbon isotope analysis of fossil pollen could be used as a proxy for reconstruction of summer moisture availability, while analysis of UACs in fossil pollen could be used as a proxy for the reconstruction of summer UV-B flux. These proxies will enhance our understanding of climatic and environmental change in Northwest Africa and will complement existing palynological techniques for environmental and climate reconstruction. Palynology, the study of organic microfossils, is an important tool for improving our understanding of past environments and landscapes. Palynology provides a wealth of information from which climatic and environmental conditions can be inferred. However, inferred climatic and environmental conditions are often open to interpretation. Assumptions made about past climate conditions from pollen assemblages often rely on qualitative understanding of modern-day vegetation distributions, rather than empirical relationships. Historic anthropogenic impact on the environment must also be inferred, and assessments made as to whether vegetation changes are a result of climate change or human impact. This study seeks to address some of the questions that arise through the interpretation of pollen assemblages, by establishing empirical relationships between the geochemistry of modern pollen and climate or environmental controls. It focuses on the pollen of the climatically sensitive montane conifer Cedrus atlantica, which is distributed across the mountains of Morocco and Algeria. The study investigates aspects of modern pollen geochemistry and morphology and finds a strong relationship between the stable carbon isotope composition of modern pollen and mean annual precipitation (r2 = 0.54, p <0.001) and summer precipitation (r2 = 0.63, p <0.0001). Furthermore, a stronger relationship exists with aridity measured using the self-calibrating Palmer Drought Severity Index (r2 = 0.86, p <0.0001), suggesting that the stable carbon isotope composition of Cedrus atlantica pollen is influenced by environmental moisture availability. The study also finds there is an increased abundance of ultraviolet absorbing compounds (UACs) in modern Cedrus atlantica pollen with increasing summer UV-B flux. This relationship was evident with samples growing in their native range (r2 = 0.84, p <0.0001), but not with samples from outside this range (r2 = 0.00, p = 0.99), suggesting a possible genetic influence. Lastly, the study finds that grain size of Cedrus atlantica pollen is highly variable within and between samples, and we rule out climatic control on pollen grain size. These results suggest that quantitative relationships can be established between the geochemistry of Cedrus atlantica pollen and environmental and climatic influences. Stable carbon isotope analysis of fossil pollen could be used as a proxy for reconstruction of summer moisture availability, while analysis of UACs in fossil pollen could be used as a proxy for the reconstruction of summer UV-B flux. These proxies will enhance our understanding of climatic and environmental change in Northwest Africa and will complement existing palynological techniques for environmental and climate reconstruction.

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Dissertations / Theses on the topic 'Analytical Chemistry Techniques'

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