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McGill, Robert Andrew. "Physicochemical measurements by gas chromatography." Thesis, University of Surrey, 1988. http://epubs.surrey.ac.uk/847792/.
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First the method of gas-liquid chromatography (GLC) has been used to obtain partition coefficients, K, at infinite dilution on polymeric and non-polymeric phases. About 30-40 solutes were studied per stationary phase. Secondly the method of gas-solid chromatography has been used to obtain adsorption isotherms for a series of adsorbents by the technique of elution by characteristic point (ECP). A single injection of a gas or vapour suffices to obtain the isotherm, and then the limiting Henry's law constant, Kh, for adsorption at low surface coverage. About 20-30 solutes were studied per adsorbent. Experiments were carried out at several levels of relative humidity (RH) 0%, 31% and 53%. The solute compounds used were chosen so as to have a wide range of properties such as polarity (pi*2), hydrogen-bond acidity (alpha[H]2), and hydrogen-bond basicity (beta[H]2). The results as log partition coefficients or -log Henry's constants were analysed by multiple linear regression analysis using equations such as: -LogK[H] or LogK = SPo + s.pi* 2 + a.alpha[H]2 + b.beta[H]2 + 1. LogL[18] where L[18] is the solute Ostwald absorption coefficient on n-hexadecane. In this way, the selectivity of the liquid polymeric phase or solid adsorbent towards classes of compound was investigated and equations for the prediction of further values of LogK or LogK[H] formulated. In parallel with the measurement of partition coefficients on liquid polymeric phases by GLC in this work, partition coefficients for the polymers have been determined using surface acoustic wave (SAW) devices by coworkers at the Naval Research Laboratory, Washington. The results for a series of 8-9 solutes in six polymeric phases show that partition coefficients and patterns of responses predicted through GLC experiments are the same as those found experimentally using coated SAW devices. Hence GLC can be used to evaluate possible coating materials, and by the technique of multiple linear regression analysis, to predict SAW responses for a multitude of vapours.
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Muralidharan, Abishek. "Evaluation of heavy-duty engine exhaust hydrocarbon and non-methane hydrocarbon analysis methods." Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5520.
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Thesis (M.S.)--West Virginia University, 2007.Title from document title page. Document formatted into pages; contains viii, 87 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 72-73).
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Ho, Sai Hang. "Analysis of airborne organic compounds using thermal desorption- gas chromatography-mass spectrometry methods /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202004%20HO.
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Kloskowski, Adam. "Improved methods for enrichment of organic ultra trace components for analysis by gas chromatography." Licentiate thesis, KTH, Chemistry, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1661.
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This thesis describes some new methods for analysis oforganic trace components from air and water by gaschromatography. The work is particularly focused on thedevelopment of new technologies for analyte enrichment, usingsorbent-based concepts. Short lengths of open tubular columnswere examined for their potential use as denuders.Polydimethylsiloxane-based stationary phases as well as anadsorbent-based column were evaluated in an equilibrium mode oftrapping. For the analytes selected, detection levels in theppb range were obtained (Paper I).
A new, fully automated set-up for analysis of organic tracecomponents in aqueous samples has been developed (Paper II).The work combines specific advantages of the solid phase microextraction (SPME) technology and stir bar sorptive extractionconcept. Ultra trace components, down to 0.1 ppt could bedetected. Finally a simple method for preparation a new type ofultra thick film open tubular trap is described (Paper III).The traps are characterized by an irregular coating, and it wasdemonstrated that the performance characteristics of thesetraps were practically as good as of traps with a smooth,regular coating. The technology can be utilized in many areas,e.g. environmental monitoring, process analysis and otherfields dealing with analysis of trace organic volatiles ingaseous samples.
Keywords:Organic trace components, volatiles, denuders,sorbent trapping, thick film trapping, open tubular traps,SPME, automation, water analysis, gas analysis, environmentalanalysis.
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Kouremenos, Konstantinos A., Mikael Johansson, and Philip J. Marriott. "Advances in gas chromatographic methods for the identification of biomarkers in cancer." Umeå universitet, Institutionen för molekylärbiologi (Medicinska fakulteten), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-61275.
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Screening complex biological specimens such as exhaled air, tissue, blood and urine to identify biomarkers in different forms of cancer has become increasingly popular over the last decade, mainly due to new instruments and improved bioinformatics. However, despite some progress, the identification of biomarkers has shown to be a difficult task with few new biomarkers (excluding recent genetic markers) being considered for introduction to clinical analysis. This review describes recent advances in gas chromatographic methods for the identification of biomarkers in the detection, diagnosis and treatment of cancer. It presents a general overview of cancer metabolism, the current biomarkers used for cancer diagnosis and treatment, a background to metabolic changes in tumors, an overview of current GC methods, and collectively presents the scope and outlook of GC methods in oncology.
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Nezami, Ranjbar Mohammad Rasoul. "Novel Preprocessing and Normalization Methods for Analysis of GC/LC-MS Data." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/73499.
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We introduce new methods for preprocessing and normalization of data acquired by gas/liquid chromatography coupled with mass spectrometry (GC/LC-MS). Normalization is desired prior to subsequent statistical analysis to adjust variabilities in ion intensities that are not caused by biological differences. There are different sources of experimental bias including variabilities in sample collection, sample storage, poor experimental design, noise, etc. Also, instrument variability in experiments involving a large number of runs leads to a significant drift in intensity measurements. We propose new normalization methods based on bootstrapping, Gaussian process regression, non-negative matrix factorization (NMF), and Bayesian hierarchical models. These methods model the bias by borrowing information across runs and features. Another novel aspect is utilizing scan-level data to improve the accuracy of quantification. We evaluated the performance of our method using simulated and experimental data. In comparison with several existing methods, the proposed methods yielded significant improvement. Gas chromatography coupled with mass spectrometry (GC-MS) is one of the technologies widely used for qualitative and quantitative analysis of small molecules. In particular, GC coupled to single quadrupole MS can be utilized for targeted analysis by selected ion monitoring (SIM). However, to our knowledge, there are no software tools specifically designed for analysis of GS-SIM-MS data. We introduce SIMAT, a new R package for quantitative analysis of the levels of targeted analytes. SIMAT provides guidance in choosing fragments for a list of targets. This is accomplished through an optimization algorithm that has the capability to select the most appropriate fragments from overlapping peaks based on a pre-specified library of background analytes. The tool also allows visualization of the total ion chromatogram (TIC) of runs and extracted ion chromatogram (EIC) of analytes of interest. Moreover, retention index (RI) calibration can be performed and raw GC-SIM-MS data can be imported in netCDF or NIST mass spectral library (MSL) formats. We evaluated the performance of SIMAT using several experimental data sets. Our results demonstrate that SIMAT performs better than AMDIS and MetaboliteDetector in terms of finding the correct targets in the acquired GC-SIM-MS data and estimating their relative levels.Ph. D.
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Geng, Dawei. "Gas chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry methods for the determination of environmental contaminants." Doctoral thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-51727.
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The recent developments and improvements of instrumental methods for the analyses of the environmental contaminants, especially the persistent organic pollutants (POPs), have made it possible to detect and quantify these at very low concentrations in environmental and biotic matrices. The main objective of this thesis is to demonstrate the capability of the atmospheric pressure chemical ionization technique (APCI), using gas chromatography coupled to tandem mass spectrometry for the determination of a wide range of environmental contaminants, including the POPs regulated by Stockholm Convention, such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), but also the derivates of PBDEs and novel brominated flame retardants (NBFRs). The APCI was operated in charge transfer condition, preferably producing molecular ions. Multiple reaction monitoring (MRM) experiments were optimized by adjusting cone voltage, collision energy and dwell time. Optimization of source parameters, such as gas flows and temperatures was also performed. Low concentration standards were analyzed, achieving a visible chromatographic peak for 2 fg 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) demonstrating the excellent sensitivity of the system. Adequate linearity and repeatability were observed for all the studied compounds. The performance of APCI methods was validated against the conventional methods using gas chromatography coupled to high resolution mass spectrometry for chlorinated compounds in a wide range of matrices including environmental, air, human and food matrices. The GC-APCI-MS/MS method was successfully applied to a set of 75 human serum samples to study the circulating levels of POPs in epidemiologic studies. Moreover the method was utilized to establish temporal trends of POPs in osprey eggs samples collected during the past five decades.
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Marsol, i. Vall Alexis. "Gas chromatography-mass spectrometry for the analysis of metabolomic compounds in agrifood products. New methods and applications." Doctoral thesis, Universitat de Lleida, 2017. http://hdl.handle.net/10803/403491.
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Aquesta Tesi Doctoral se centra en el desenvolupament de nous mètodes de cromatografia de gasos acoblada a tècniques d'espectrometria de masses (GC-MS) i a l'aplicació d'alguns mètodes ja existents a l'anàlisi de mostres de fruites i derivats. La tesi es divideix en tres parts segons els enfocaments estudiats.
Inicialment, es va desenvolupar un mètode de cromatografia de gasos bidimensional comprensiva (GC×GC-MS) en la qual es van provar diverses configuracions de columnes. A la segona part de la Tesi, es van desenvolupar tres nous mètodes basats en la derivatització al port d'injecció. La primera va consistir en l’anàlisi selectiu de 17 polifenols glicosilats i no glicosilats en mostres de fruita i suc de fruita. El segon mètode es va destinar a l'anàlisi de HMF i patulina, dos compostos utilitzats com a marcadors de qualitat en la indústria dels sucs de fruites. L'últim mètode desenvolupat en aquesta part es va centrar en la fracció lipofílica lliure de sucs de fruita. En aquest cas, una microextracció líquid-líquid dispersiva (DLLME) va precedir a la derivatització en el port. La tercera part es va centrar en l'anàlisi dels compostos volàtils i semi-volàtils de diversos derivats de la fruita, a saber, fibres de fruita derivades de la indústria dels sucs i quatre mostres de sucs de préssec consistents en dues varietats (groc i vermell) i dos procediments d'elaboració per a cada varietat (recentment liquat i comercial).This Doctoral Thesis focuses on the development of novel gas chromatography coupled to mass spectrometry (GC-MS) techniques and the application of some existing methods to the analysis of fruit and fruit-derived samples. The thesis is divided in three parts attending the approaches studied. Initially, a comprehensive two-dimensional gas chromatography (GC×GC-MS) method was developed by testing several column configurations to analyse apples and peaches. In the second part of the Thesis, three new methods based on injection-port derivatization were developed. The first consisted on a targeted analysis of 17 glycosylated and non-glycosylated polyphenols in fruit and fruit juice samples. The second method was devoted to the analysis of HMF and patulin, two compounds used as markers of quality in the fruit juice industry. The last method developed in this part was focused on the free lipophilic fraction of fruit juices. In this case, a dispersive liquid-liquid microextraction (DLLME) preceded in-port derivatization. The third part was devoted to the analysis of volatile and semi-volatile compounds in several fruit-derived products, namely fruit fibres deriving from the juice industry and four samples of peach juices consisting in two varieties (yellow and red-fleshed) and two distinct processing procedures for each variety (freshly blended and commercial).
Esta Tesis Doctoral se centra en el desarrollo de nuevos métodos de cromatografía de gases acoplada a técnicas de espectrometría de masas (GC-MS) y a la aplicación de algunos métodos existentes al análisis de muestras de frutas y derivados. La tesis se divide en tres partes según los enfoques estudiados. Inicialmente, se desarrolló un método de cromatografía de gases bidimensional comprensiva (GC×GC-MS) en la que se probaron varias configuraciones de columnas. En la segunda parte de la Tesis, se desarrollaron tres nuevos métodos basados en la derivatización en el puerto de inyección. La primera consistió en un análisis selectivo de 17 polifenoles glicosilados y no glicosilados en muestras de fruta y zumo de fruta. El segundo método se dedicó al análisis de HMF y patulina, dos compuestos utilizados como marcadores de calidad en la industria del zumo de frutas. El último método desarrollado en esta parte se centró en la fracción lipofílica libre de zumos de fruta. En este caso, una microextracción líquido-líquido dispersiva (DLLME) precedió a la derivatización en el puerto. La tercera parte se dedicó al análisis de los compuestos volátiles y semi-volátiles de varios derivados de la fruta, a saber, fibras de fruta derivadas de la industria de los zumos y cuatro muestras de zumos de melocotón consistentes en dos variedades (amarillo y rojo) y dos procedimientos de elaboración para cada variedad (recién licuado y comercial).
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Ghasemi, Damavandi Hamidreza. "Data analytics, interpretation and machine learning for environmental forensics using peak mapping methods." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/2083.
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In this work our driving motivation is to develop mathematically robust and computationally efficient algorithms that will help chemists towards their goal of pattern matching. Environmental chemistry today broadly faces difficult computational and interpretational challenges for vast and ever-increasing data repositories. A driving factor behind these challenges are little known intricate relationships between constituent analytes that constitute complex mixtures spanning a range of target and non-target compounds. While the end of goal of different environment applications are diverse, computationally speaking, many data interpretation bottlenecks arise from lack of efficient algorithms and robust mathematical frameworks to identify, cluster and interpret compound peaks. There is a compelling need for compound-cognizant quantitative interpretation that accounts for the full informational range of gas chromatographic (and mass spectrometric) datasets. Traditional target-oriented analysis focus only on the dominant compounds of the chemical mixture, and thus are agnostic of the contribution of unknown non-target analytes. On the other extreme, statistical methods prevalent in chemometric interpretation ignore compound identity altogether and consider only the multivariate data statistics, and thus are agnostic of intrinsic relationships between the well-known target and unknown target analytes. Thus, both schools of thought (target-based or statistical) in current-day chemical data analysis and interpretation fall short of quantifying the complex interaction between major and minor compound peaks in molecular mixtures commonly encountered in environmental toxin studies. Such interesting insights would not be revealed via these standard techniques unless a deeper analysis of these patterns be taken into account in a quantitative mathematical framework that is at once compound-cognizant and comprehensive in its coverage of all peaks, major and minor.
This thesis aims to meet this grand challenge using a combination of signal processing, pattern recognition and data engineering techniques. We focus on petroleum biomarker analysis and polychlorinated biphenyl (PCB) congener studies in human breastmilk as our target applications.
We propose a novel approach to chemical data analytics and interpretation that bridges the gap between target-cognizant traditional analysis from environmental chemistry with compound-agnostic computational methods in chemometric data engineering. Specically, we propose computational methods for target-cognizant data analytics that also account for local unknown analytes allied to the established target peaks. The key intuition behind our methods are based on the underlying topography of the gas chromatigraphic landscape, and we extend recent peak mapping methods as well as propose novel peak clustering and peak neighborhood allocation methods to achieve our data analytic aims. Data-driven results based on a multitude of environmental applications are presented.
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Armstrong, Helen Elisabeth Louise. "Speciation of mercury by chromatography coupled with atomic spectrometry." Thesis, University of Plymouth, 2000. http://hdl.handle.net/10026.1/1868.
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A commercial GC-AFS instrument has been developed and optimised for the speciation of organomercury. This instrument couples a GC oven to a modified atomic fluorescence detector via a ceramic pyrolyser. Organomercury compounds in dichloromethane solvent were directly injected through a Programmable Temperature Vaporiser Injector onto a DBl Megabore column. Once separated, the compounds eluted from the column and were atomised in the pyrolyser then detected by AFS. The direct injection technique, ceramic pyrolysis design and argon purged detector have improved previous instrument designs by enhancing and maintaining sensitivity. The instrumental limit of detection was determined to be 0.25 pg Hg absolute. Methods were developed for the extraction of methylmercury from a variety of marine samples. The techniques were validated using mussel homogenate and dogfish liver (IAEA 142, SRM 8044 and DOLT-2) certified reference materials. An interlaboratory comparision exercise was participated in and a method was developed for the detemination of methylmercury in Fucus sea plant (IAEA 140). A concentration of 0.63 ± 0.006 ng g-1 was reported. The material is now certified at 0.626 +0.139 ng g-1. Of all the participating laboratories, this was the closest result to the certified value. The instrument and methods were also applied to soil and sediment samples. Once again validation was performed with a CRM sediment, IAEA 356. Although this material has been reported to give positive artifact formation when using a steam distillation sample preparation procedure, good agreement and no artifects were observed upon analysis. A further contaminated land, an uncontaminated soil and sediment sample were also studied. For all the samples studied by GC-AFS total mercury measurements were also made following an appropriate digestion procedure and CV-AFS. A gas chromatograph was also coupled with ICP-MS and HPLC was coupled to CV-AFS as comparative techniques. Both approaches were optimised and validated with CRM's. The GC-ICP-MS had the advantage of providing additional element information and confirmed the presence of methylmercury bromide in the final mussel homogenate extract. The HPLC approach found to be much less sensitive than the GC techniques and also suffered from vapour generation interferences. The PTV injector was considered for large volume injection and thermal desorption techniques. Injector breakdown problems were overcome by optimising the conditions and solid phase adsorbent for cold splitless injection. A recovery of 70% was achieved for a 50 ul large volume injection of methylmercury chloride in DCM. This technique indicated the possibility that LVI may in the future offer increased method sensitivity.
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Sarnoski, Paul J. "Instrumental Methods for Determining Quality of Blue Crab (Callinectes sapidus) Meat." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/32810.
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The purpose of this study was to find an alternative instrumental method to sensory analysis and to further investigate the aroma properties of spoiling blue crab meat. This was accomplished by use of a Cyranose 320â ¢ Electronic Nose, Draeger-Tubes®, and solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC-MS). These techniques were compared to the more established techniques for determining quality of blue crab meat of sensory and microbiological analysis. Three different electronic nose methods were used to evaluate five sequentially spoiled groups of crab meat. The manufacturerâ s recommended setup only resulted in a 30 % correct separation of the known groups, and only 10 % of the samples were correctly identified when coded unknown samples were used to validate the electronic nose training results. The compressed air method which utilized compressed tank breathing air, filtered through activated carbon and moisture traps resulted in 100 % separation of the known groups, but only correctly identified 20 % of the coded unknown samples. Draeger-Tubes® were found to be more accurate and precise compared with the electronic nose. All 5 groups of samples analyzed using Draeger-Tubes® were found to be significantly different at α = 0.05 using a Tukey-Kramer ANOVA statistical procedure. The coded unknown samples were correctly identified at a rate of 83 %. The simplicity and rapidness of this procedure allows it to possibly be an alternative for the crab industry as an alternative to sensory analysis.
SPME-GC-MS found trimethylamine (TMA), ammonia, and indole to best correlate with spoilage of blue crab meat. TMA was found to be sensitive to the minor changes in the early stages (0 - 4 days of refrigerated storage) of spoilage for blue crab meat. Indole corresponded well with sensory results, which suggests that indole may be a promising indicator for detecting early, mid, and highly spoiled samples. It is feasible that these methods can be applied to other crustaceans to determine spoilage level.Master of Science in Life Sciences
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Conner, Laura. "Evaluation of field sampling and analysis methods for fire investigation including electronic noses and adsorption sampling/gas chromatography mass spectrometry." FIU Digital Commons, 2005. http://digitalcommons.fiu.edu/etd/2422.
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This study evaluates the use of commercially available instruments for locating and collecting accelerants in the field. Electronic noses can be used to scan a fire scene for the possible presence of an accelerant. The TLV Sniffer® was found to be able to detect accelerants at low levels but did alert to some burned matrix alone. When subjected to a proficiency test designed for canines, the TLV Sniffer® was able to locate accelerants in two of the three tests. The tpi®Pocket was found not to be sensitive or selective enough to be useful in locating accelerants. Once the location of possible accelerants has been determined, they can be collected by dynamic headspace sampling in the field with the Portable Arson Sampler (PAS). The PAS was found to be able to collect a broad range of compounds from ignitable liquids and had comparable efficiency to a conventional method.
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Waters, Laura S. "Comparison of two methods for differentiating negative from inconclusive GC-MS test results using an isotopic analog of the analyte as the internal standard -- 11-nor-[delta]⁹-tetrahydrocannabinol-9-carboxylic acid example." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2008m/waters.pdf.
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Burman, Lina. "Chromatography and extraction techniques for new evaluation methods of polyolefins long-term performance." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-219.
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Johnsson, Lars. "Phytosterol oxidation products : formation, analysis and occurrence /." Uppsala : Dept. of Food Science, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/a490.pdf.
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Zulfiqar, Adnan. "The development and evaluation of methods for the screening of steroids using molecular imprinted polymers coupled with comprehensive gas chromatography/mass spectrometry and aptamers coupled with liquid chromatography/mass spectrometry." Thesis, Open University, 2016. http://oro.open.ac.uk/47962/.
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The profiling of hormones is an important requirement in sports dope testing and it is increasingly being used for clinical applications. The screening of samples for the detection of steroids is usually undertaken in urine and these analyses present many challenges. Issues related to the complexity of the matrix, the separation of exogenous from endogenous species and the very low detection limits have placed increasing demands on clinical and International Olympic Commission accredited laboratories. Whilst liquid chromatography (LC) systems provide a highly sensitive detection method for targeted species, gas chromatography, especially when coupled to mass spectrometry, is considered preferable for the screening of a wider range of target and unknown species. Existing chromatography methods are not without their limitations, not least the difficulty in reproducibly derivatising the wide range of steroids that can be exogenously administered, in particular the so called ‘designer steroids’ which deliberately hinder this process. Initially, a pilot study was conducted to investigate whether aptamer-coated magnetic beads could provide a simple, low cost method for the extraction of estradiol from urine, prior to its detection and quantification with mass spectrometry. In reality, the process necessitated the use of additional solvent extraction steps to the standard method applied previously. These additional steps added complexity and were not without issue and the limit of detection was not found to be adequate for the proposed clinical purpose. The project explored the application of comprehensive gas chromatography/mass spectrometry (GC x GC/MS) coupled to bespoke molecular imprinted polymers (MIPS) as an alternative solution to the problem of the screening of multiple steroids in urine. Twelve structurally similar and commercially relevant steroids were used to develop the chromatographic method. Once optimised, these compounds were then extracted from synthetic urine using a MIP templated with testosterone and developed during the project. Significant improvements compared to commercially available C-18 materials were found. All the steroids were identified and detected when spiked at the 10 ng/ml level, as required by World Anti-Doping Agency (WADA) at the time. The method was further validated and then successfully applied to the extraction of designer steroids from synthetic urine, in the presence of the original steroids. Epistane, which has a different structure to testosterone, was not detected indicating the efficacy of the templating process.
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Turner, Diane Coral. "The development and evaluation of non-invasive methods to characterise the disease states of patients utilising selective discrimination, gas chromatography-mass spectrometry and chemometrics." Thesis, Open University, 2018. http://oro.open.ac.uk/53802/.
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The ‘smell’ of illness, disease or age has been known for many centuries, mainly created by volatile organic compounds (VOCs). Dogs were first reported to detect cancer in 2004. Increasingly, the profiles of VOCs are being utilised as non-invasive diagnostic methods. The aim of the thesis was to develop and evaluate the performance of analytical methods to characterise the disease states of patients utilising selective discrimination, gas chromatography-mass spectrometry (GC-MS) and chemometrics. The primary analytical technique investigated was GC-Time-of-Flight-MS coupled with headspace solid-phase microextraction (HS-SPME-GC-ToFMS). A robust and sensitive method was developed by optimisation of all sample analysis parameters and was applied to clinical samples from bladder and prostate cancer patients and those with hepatic disorders. This evidence was obtained by quantifying an internal standard, present in every sample and blank throughout the studies. Based on these findings, large numbers of clinical samples were analysed with confidence. Statistically significant mathematical models were developed in partnership with Cranfield University to classify the diseased state of samples and clinically relevant controls. PLS-DA was determined as the best classifier. The results from the HS-SPME-GC-ToFMS studies were highly promising. Bladder cancer gave a mean accuracy of >80 % and even low-grade tumours gave a sensitivity of 73 %, superior to urine cytology. Higher clinical performance was obtained in the prostate cancer study, with BPH distinguishable from cancer. Hepatic disorders were better again (>86 %). Preliminary studies on sepsis detection also showed promise. Several recommendations were made to enable significant clinical results in the future based on analytical rigour.
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Kociánová, Veronika. "Organohalogenové sloučeniny - kontaminanty životního prostředí." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2013. http://www.nusl.cz/ntk/nusl-216948.
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Polybrominated diphenyl ethers belong to group of brominated flame retardants. Important property of these substances is their ability to reduce flammability or to prevent ignition of many products of daily use, such us televisions, carpets, mattresses and many others. Polybrominated diphenyl ethers however are characterized by high persistence and lipophility, leading to their accumulation in the environment. In recent years, concerns about the effects of organic halogen compounds on human health, suggesting their inclusion in the list of persistent organic pollutants in 2009. These contaminants are capable of long-range transport and accumulation in the environment. Therefore, the presence of polybrominated diphenyl ethers is systematically observed in the abiotic and biotic components of the environment worldwide. Their presence has been demonstrated in areas that are clearly very distant from sources of contamination. This thesis is focused on the use of gas chromatography to assess the level of contamination of selected components of the environment, especially of soil. For these purposes was used method of gas chromatography with electron capture detection mass spectrometry.
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Hamalčíková, Veronika. "Necílený screening organických polutantů ve vodách a sedimentech." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-216788.
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This master thesis deals with the potential influence of the waste dump Hrádek u Pacova and the wastewater treatment plant Brno – Modřice on surroundings using the optimized non-target screening method of organic pollutants in water and sediments. The experimental part is focused on the identification of organic compounds in samples of ground water from monitoring wells, the surface water from stream and pond and in sediment samples collected from streams in the vicinity of municipal waste dump. Organic compounds were also identified in water and sediment samples from the river Svratka near the municipal waste water treatment plant Modřice. The sequential liquid – liquid extraction was used for the isolation of organic compounds in water samples. Organic compounds in sediment samples were isolated by pressurized solvent extraction (PSE) with subsequent fractionation of the extract using column chromatography. Final analysis determination was performed using comprehensive orthogonal two-dimensional gas chromatography with mass spectrometric detection (GCxGC-TOF MS).
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Avillez, Maria Vaz Pinto d’. "Part I : Comparing derivatization methods for amino acids – one and two-step procedures using gas chromatography – flame ion detector (GC-FID) Part II: Story of an icon from its execution until its conservation." Master's thesis, FCT - UNL, 2007. http://hdl.handle.net/10362/3613.
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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de
Lisboa para obtenção do grau de Mestre em Conservação e RestauroTwo derivatization methods were tested in twenty-one standard amino acids (AAs) for further identification and quantification by the analytical technique of Gas Chromatography with Flame Ion Detector (GC-FID). For the one-step derivatization reaction N-methyl-N (tert.- butyldimethylsilyl)trifluoroacetamide (MTBSTFA) was used and for the two-step reaction we used hydrochloridic acid (HCl) and trifluoroacetic anhydride (TFAA). We obtained better results with the derivatization procedure in two-steps, although it takes longer, and we concluded that the reproducibility of these reactions is difficult to achieve.
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Brown, Veronica M. "Development of improved methods for the characterisation of organic chemicals emitted into indoor air by building and furnishing products." Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/8078.
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A wide range of organic compounds are released from building and furnishing products and these have the potential to adversely affect indoor air quality. There are growing international requirements for testing and controlling these emissions for the protection of public health. The test methods require specialist analytical chemistry facilities based on thermal desorption/gas chromatography/mass spectrometry (TD/GC/MS). This project has addressed the need for better performance and greater automation of the analysis, as well as development of simpler screening tests. A variety of products were tested using screening techniques, with an emission cell method being used as a reference test. Short duration tests, using a micro-scale chamber at slightly elevated temperature, were shown to have the potential to predict emissions occurring during longer term reference tests. Multi-sorbent air sampling tubes, that have the potential to extend the volatility range of compounds determined by a single TD/GC/MS analysis, were compared with Tenax TA tubes specified by current standard methods. This showed no difference in performance for the range of compounds for which Tenax is optimal, with improved performance for a number of more volatile compounds. The determination of formaldehyde was investigated using 2-hydroxymethylpiperidine as a derivatising agent, followed by TD/GC/MS. The results showed the possibility of this method being developed as an alternative to the current standard method that involves solvent elution and liquid chromatography. The performance of a newly developed time-of-flight mass spectrometer was compared with a standard quadrupole instrument. This showed its potential, with the use of re-collection, to extend the concentration range of compounds quantified from a single air sample, of particular benefit for the determination of carcinogens. New compound identification software was applied to increase automation of analysis of the TD/GC/MS data. Good correlation with manual processing was achieved, demonstrating the possibility of routine application to material emissions testing.
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Eser, Hülya Tıhmınlıoğlu Funda. "Diffusion And Equilibrium Measurements In Polymer-Solvent Systems By Inverse Gas Chromatography Method/." [s.l.]: [s.n.], 2004. http://library.iyte.edu.tr/tezler/master/kimya/T000451.pdf.
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Chappell, Colin Graham. "Multidimensional liquid and gas chromatographic methods for veterinary drug analysis." Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357971.
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Chihara, Kazuyuki, Hidenori Nakamura, and Yosuke Kaneko. "Diffusion study of multi-component gas adsorption in MSC5A by chromatographic method: Diffusion study of multi-component gas adsorption in MSC5Aby chromatographic method." Diffusion fundamentals 6 (2007) 57, S. 1-2, 2007. https://ul.qucosa.de/id/qucosa%3A14236.
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Charreteur, Claude. "Apports des méthodes et techniques de couplage à l'analyse des pesticides dans les eaux." Brest, 1997. http://www.theses.fr/1997BRES2021.
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La concentration maximale fixée par les pays de l'union européenne, pour tout pesticide présent dans les eaux destinées à la consommation humaine, est de 0,10 g/l. Pour atteindre ces limites, il faut pouvoir doser des teneurs 2 à 3 fois inferieures, ce qui implique de travailler en limite de sensibilité des méthodes conventionnelles de chromatographie. Dans un souci d'assurance de la qualité des résultats, nous avons évalué, dans un premier temps, les apports d'une technique dite, multi-méthodes, qui associe une méthode clhp multi-résidus à des méthodes cg plus spécifiques. Pour une molécule donnée, le recoupement des résultats enregistrés par les deux méthodes permet, avec un minimum d'incertitudes, de conclure à la présence d'un pesticide dans l'eau et d'en déterminer la teneur. Cette procédure a été validée pour cinq familles de pesticides : triazines, triazoles, phenoxyacides, phenyls urees, cyano et nitro phenols. Cette approche, dans l'ensemble tout à fait satisfaisante, ne peut, dans certains cas lever totalement les doutes qui subsistent en raison de la présence des produits interférents. C’est pourquoi, nous avons, dans un second temps, cherche à améliorer la sensibilité et la spécificité des méthodes cpg en évaluant les apports de nouvelles techniques de couplage à l'analyse des produits phytosanitaires. L’injection en grand volume donne la possibilité de réduire les volumes de solvants utilises lors des étapes d'extraction et d'abaisser de manière significative les seuils de détection. Ce couplage permet donc, selon le cas de simplifier la procédure d'analyse et/ou de travailler confortablement par rapport aux limites sanitaires. La détection de masse en tandem utilisant une trappe d'ions donne une garantie de spécificité totale au niveau des produits que l'on désire doser. Nous avons mis en œuvre ces techniques dans l'analyse des phenyls urees et des triazines ; l'utilisation de ces deux techniques a, également, permis d'élaborer une méthode d'analyse multi-résidus de ces deux familles de pesticides par cpg.
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Chihara, Kazuyuki, Hidenori Nakamura, Yuki Teramura, and Yousuke Kaneko. "Study of multi-component gas adsorption by chromatographic method and simulation." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-189459.
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Chihara, Kazuyuki, Hidenori Nakamura, Yuki Teramura, and Yousuke Kaneko. "Study of multi-component gas adsorption by chromatographic method and simulation." Diffusion fundamentals 11 (2009) 23, S. 1-2, 2009. https://ul.qucosa.de/id/qucosa%3A13962.
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Akapo, S. Olufolabi. "Gas-solid fluidisation : an improved method for the preparation of chemically bonded stationary phases." Thesis, Birkbeck (University of London), 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246115.
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Andersson, Kjell. "Development of a method for comparing amphetamine samples /." Linköping : Univ, 2004. http://www.bibl.liu.se/liupubl/disp/disp2004/tek879s.pdf.
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Egeness, Mari Jystad. "Comprehensive Two-Dimensional Gas Chromatography: method development and verification by characterisation of petroleum fractions." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for kjemi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16799.
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AbstractComprehensive two-dimensional gas chromatography is a multidimensional separation technique. A sample is separated by two properties on two different columns, typically by carbon number and polarity. The two columns are connected by a modulator. The modulator is responsible for collection of three to four fractions of each 1st column separation peak, condensation of the fractions, and introducing them as a sharp narrow band onto the 2nd column. It is a continuous process of condensation of succeeding 1st column fractions and transfer to the 2nd column. The individual separations are “sewn” together by the software to produce a two-dimensional chromatogram. The abscissa displays the carbon number separation and the ordinate axis show the separation of polar compounds.Pre-set parameters such as carrier gas, gas velocities, detector temperatures, and column set were kept on recommendation by the installation contractors. Method development and optimisation was performed by exploring injection volume, oven temperature programs, and modulator time parameters. Hydrocarbon standards and petroleum fractions were analysed for determining the optimal parameter values. The result was two methods, one recommended for atmospheric gas oil (AGO) analyses and another for vacuum gas oil (VGO) analyses. Injection volumes of 0.015 to 0.002 µL gave low risk of column overload while still maintaining the abundance of compounds of low concentration. Temperature programmes of constant ramps gave good separation. A compromise between excellent separation and time of analysis resulted in using temperature ramps of 4.5 oC/min with a start and final temperature of 50 oC and 340 oC, respectively, for AGOs, and 3.5 oC/min with a start and final temperature of 150 oC and 340 oC, respectively for VGOs. A modulation time of 8000 ms and a hot jet duration of 500 ms proved to give good correlation between the 1st separation’s peak widths and the time needed for 2nd dimension separation. Straight run and processed petroleum fractions were analysed by the optimised methods. Constructed templates for dividing the sample’s polarity distribution into groups gave a distribution of volume response of all the compounds within the defined groups. The hydrocarbon analyses of the petroleum fractions were straight forward; volume responses were directly proportional to weight percent of the sample. The hydrocarbon standards gave approximately the same response factor. The same did not apply for sulphur analysis. The standards’ responses were not very reproducible, and the response factors were not similar for the polarity classes. Identification of sulphur compounds in AGOs and VGOs is possible although quantification is not recommended at the present. The methods showed to give good separation of both AGOs and VGOs. Although further optimisation especially of sulphur analysis, is highly encouraged.
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Chihara, Kazuyuki, Hidenori Nakamura, and Yosuke Kaneko. "Diffusion study of multi-component gas adsorption in MSC5A by chromatographic method." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-193932.
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Martin, Danica Paige. "Optimization of a Method for the Extraction of Drugs of Abuse from Wastewater." Bowling Green State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1617014087323429.
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Xu, Guang. "Development of a remote analysis method for underground ventilation systems using tracer gas and CFD." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/19312.
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Following an unexpected event in an underground mine, it is important to know the state of the mine immediately to manage the situation effectively. Particularly when part or the whole mine is inaccessible, remotely and quickly ascertaining the ventilation status is one of the pieces of essential information that can help mine personnel and rescue teams make decisions. This study developed a methodology that uses tracer gas techniques and CFD modeling to analyze underground mine ventilation system status remotely. After an unanticipated event that has damaged ventilation controls, the first step of the methodology is to assess and estimate the level of the damage and the possible ventilation changes based on the available information. Then CFD models will be built to model the normal ventilation status before the event, as well as possible ventilation damage scenarios. At the same time, tracer gas tests will be designed and performed on-site. Tracer gas will be released at a designated location with constant or transient release techniques. Gas samples will be collected at other locations and analyzed using Gas Chromatography (GC). Finally, through comparing the CFD simulated results and the tracer on-site test results, the general characterization of the ventilation system can be determined.
A review of CFD applications in mining engineering is provided in the beginning of this dissertation. The basic principles of CFD are reviewed and six turbulence models commonly used are discussed with some examples of their application and guidelines on choosing an appropriate turbulence model. General modeling procedures are also provided with particular emphasis on conducting a mesh independence study and different validation methods, further improving the accuracy of a model. CFD applications in mining engineering research and design areas are reviewed, which illustrate the success of CFD and highlight challenging issues.
Experiments were conducted both in the laboratory and on-site. These experiments showed that the developed methodology is feasible for characterizing underground ventilation systems remotely. Limitations of the study are also addressed. For example, the CFD model requires detailed ventilation survey data for an accurate CFD modeling and takes much longer time compared to network modeling.
Some common problems encountered when using tracer gases in underground mines are discussed based on previously completed laboratory and field experiments, which include tracer release methods, sampling and analysis techniques. Additionally, the use of CFD to optimize the design of tracer gas experiments is also presented. Finally, guidelines and recommendations are provided on the use of tracer gases in the characterization of underground mine ventilation networks.Ph. D.
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Zethelius, Thea. "Development of headspace solid phase microextraction gas chromatography mass spectrometry method for analysis of volatile organic compounds in board samples : Correlation study between chromatographic data and flavor properties." Thesis, Karlstads universitet, Institutionen för ingenjörs- och kemivetenskaper (from 2013), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-84941.
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The purpose of this thesis work was to develop a headspace solid phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS) method to detect volatile organic compounds (VOCs) in board samples and to statistically investigate potential correlation between chromatographic data and flavor data obtained from a trained panel. The developed method would hopefully serve as a complement to the already established routine analyses at Stora Enso and gain an increased understanding of which VOCs in the board influence its flavor properties. The impact of incubation time and adsorption time on the area under curve (AUC) was studied with a Design of Experiment screening using the software MODDE. The screening data showed a correlation between large AUC and low repeatability measured as relative standard deviation (RSD). The data was hard to fit to a model due to the large RSD values for the replicates, AUC for identified compounds as response gave an acceptable fit. The regression coefficients for the model showed that a longer adsorption time gave larger AUC, while incubation time had no significant impact on the response. Instead of following up the screening with an optimization, the focus was shifted to improving the repeatability of the method, i.e. lowering the RSD. The high RSD was believed to mainly be the result of leakage of analytes and unstable temperature during adsorption, preventing the system from reaching equilibrium. Different heating options and capping options for the vial was tested. Septum in crimp cap ensured a gas tight seal for the vial, giving lower RSD values and larger AUC compared to the other alternatives, showing that there was indeed a leakage. Using oil bath ensured stable temperature during the adsorption and detection of a larger number of VOCs but created a temperature gradient in the vial due to it not being fully submerged in the oil. Oil bath gave larger AUC, but still high RSD due to the temperature gradient making the method sensitive to variance in fiber depth in the vial. The final method was performed with 2 g of board sample in a 20 ml headspace vial sealed with a crimp cap with septa. The incubation and adsorption were performed with the vial immersed in a 90-degree oil bath. 20 min incubation time was chosen based on the time it took to get a stable temperature gradient in the vial, and 20 minutes adsorption time was chosen as a good compromise between large AUC and low RSD. Compared to Stora Ensos routine analysis, the developed SPME method gave chromatograms with an improved signal-to-noise ratio for the base line and several more peaks with larger AUC. For the board sample used during method development, the SPME-method identified 34 VOCs, while the routine analysis only identified 12. The developed method was applied on 11 archived board samples of the same quality that were selected based on their original flavor properties, to get a large diversity of samples. Flavor analysis was performed by letting a trained flavor panel describe the flavor based on intensity and character of the water that had individually been in indirect contact with one of the 11 board sample for 24 h. Potential correlation between chromatographic data obtained with the developed method and the flavor experience described by the flavor panelists was statistically investigated with the multivariate analysis software SIMCA. The correlation study showed that a combination of 12 VOCs with short retention time are most likely the main source of off-flavor which of 5 could only be identified with the developed SPME method. VOCs with long retention time did not contribute to an off-flavor and might have a masking effect on flavor given by other VOCS, however not confirmed in this study. Furthermore, the age of the board samples proved to be a good indicator for prediction of the flavor intensity, whereas the total AUC of the samples was not. Possible correlation between detected VOCs in the samples and flavor character given by the flavor panel were seen, however the variation in the data and the sample set were too small, preventing from making conclusions on individual VOCs impact on the flavor experience. The developed HS-SPME-GC-MS method would serve as a complement to the already established routine analyses at Stora Enso and has slightly increased the understanding of which VOCs in the board influence the flavor properties
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Weller, Marc F. "Advanced Oxidation Treatment for Ibuprofen, Ketoprofen, and Naproxen in Water and Method for Determining Ibuprofen, Ketoprofen, and Naproxen Concentration using LLE-GC-FID." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/99.
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Pharmaceuticals are a group of emerging organic compounds of environmental concern used extensively in human and veterinary medicine. They are continually released into the environment as a result of manufacturing operations and excretion from humans and animals. These compounds enter directly into the municipal sewage systems and into wastewater treatment plants. A large number of important and potentially harmful organic contaminants, such as these pharmaceuticals, are not regulated in drinking and other waters. As a result, conventional technologies at most waste water treatment plants (WWTPs) discharge water that meet regulatory standards, yet are not specifically designed to remove these organic contaminants. Therefore, pharmaceutical compounds and their metabolites remain in discharged effluent and enter into the natural aquatic environment. Concentrations of pharmaceutical residues measured in water are typically reported in the ranges of ug/L to ng/L, which are at least three to four orders of magnitude lower than that required to produce a pharmacological effect. The probability of risks to humans arising from such an acute exposure is unlikely, but the possible effects resulting from life-long exposures and synergistic effects from exposure to many chemicals have yet to be determined. It has been widely reported that pharmaceuticals and their metabolites that enter into the aquatic environment can have a potential harmful effect on the aquatic ecosystem and can reach drinking water sources. This research focuses on non-steroid anti-inflammatory drugs (NSAIDs), a group of pharmaceuticals which are widely used as analgesic, antipyretic and anti-inflammatory agents. NSAIDs are frequently used because they are easily accessible as over the counter medication and are a group of drugs that do not produce addiction, respiratory depression, or drowsiness. There is an incentive for removing NSAIDs and other pharmaceuticals from the aquatic environment. Thus, quantitative evaluation of the fate of pharmaceuticals, proper risk assessment and improvement of the efficiency of WWTPs need sensitive and reliable analytical methods. The purpose of this project was to provide a method for detecting three common NSAIDs, IBF, KTF, and NAP, in purified water with LLE-GC-FID. And, an investigation of UV photolysis, UV/H2O2, and UV/TiO2 AOPs was performed to determine their effectiveness in treating IBF, KTF, and NAP in purified water. All treatment methods were successful in degrading target compounds with a total degradation of 86% or greater after 45 minutes. A liquid-liquid extraction technique using methylene chloride and BSTFA + 1%TMCS derivatizing agent was determined for detecting low concentrations of IBF, KTF, and NAP with calibration curves showing good linearity with all R2 values greater than 0.9880.
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Hudson, Edward D. "The biogeochemistry of sterols in Trinity Bay, Newfoundland, and a new method (thin layer chromatography-pyrolysis-gas chromatography-mass spectrometry) for their analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ47458.pdf.
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Jenkins, Erica Helen. "A method for the quantitative determination of pentachlorophenol in environmental samples utilising gas chromatography/mass spectrometry." Thesis, University of Salford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238787.
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Wiklund, Susanne. "Spectroscopic data and multivariate analysis : tools to study genetic perturbations in poplar trees." Doctoral thesis, Umeå : Department of Chemistry, Umeå Univ, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1396.
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Viswakumar, Anjali. "Development of a Gas Chromatography-Tandem Mass Spectrometry Method for the Simultaneous Analysis of 19 Taste and Odor Compounds." NCSU, 2010. http://www.lib.ncsu.edu/theses/available/etd-12172009-085741/.
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An analytical method was developed to detect and quantify 19 compounds commonly associated with taste and odor (T&O) problems in drinking water. The method can be used by utilities during T&O episodes to quickly and reliably detect T&O compounds and determine their concentrations. Knowledge about the identity and concentration of T&O compounds will greatly aid utilities in the selection of appropriate treatment strategies. Head space solid phase microextraction (SPME) was used to concentrate T&O compounds, and gas chromatography (GC) followed by tandem mass spectrometry (MS/MS) was used to separate, detect, and quantify the T&O compounds. Method development included (1) determination of parent ion mass and retention time, (2) optimization of the ion trap MS/MS instrumental parameters, (3) development of calibration curves, and (4) determination of the method detection limits (MDLs) and limits of quantitation (LOQs) for each compound. For 12 of the 17 targeted T&O compounds with known odor threshold concentrations (OTCs), LOQs were below the OTC. This result suggests that the developed method is capable of detecting developing T&O problems for these 12 compounds and allow utilities to implement treatment strategies before consumers can detect objectionable tastes and odors in their water. The developed method was tested by analyzing three water samples from North Carolina ponds and lakes that experienced algae/cyanobacteria blooms. In addition, Raleigh source and tap water samples were analyzed. Of the 19 targeted T&O compounds, all but 2,4,6 tribromoanisole were detected in the collected samples. In the bloom samples, geosmin, β-ionone, and trans-2,cis-6-nonadienal most frequently occurred at concentrations that exceeded their OTCs, sometimes by a factor of >100. A comparison of results for non-filtered and filtered (0.45 µm membrane) samples suggests that many T&O compounds were predominantly present inside algae/cyanobacteria cells. Only geosmin and β-cyclocitral were present at measurable levels in Raleigh source and tap water. Concentrations in the raw and tap water samples were similar and at levels that were at or below the OTCs of geosmin and β-cyclocitral.
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STOLL, GABRIELA COSTA. "METHOD DEVELOPMENT FOR DETERMINATION OF POLYCHLORINATED BIPHENYLS (PCBS) IN SURFACE WATER BY GAS CHROMATOGRAPHY COUPLED TO TANDEM MASS SPECTROMETRY." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=35914@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
Este trabalho consistiu na implementação, e consequente validação, de metodologia para determinação de bifenilas policloradas (PCBs) em amostras de água e material particulado por cromatografia gasosa acoplada à espectrometria de massas em tandem (GC-MS/MS). O método de análise de água superficial foi desenvolvido para a determinação simultânea de 41 PCBs; utilizando a Extração Acelerada por Solvente (ASE) para o material particulado em suspensão e a Extração em Fase Sólida (SPE) para a fração dissolvida. A quantificação foi realizada no modo de Monitoramento Seletivo de Reação (SRM), com monitoramento de dois padrões de fragmentação m/z precursor-produto. A linearidade das curvas analíticas foi confirmada pelo valor do coeficiente de determinação (R2), além do comportamento aleatório do gráfico de resíduos e pelo teste F na análise da variância (ANOVA) da regressão. A homocedasticidade dos dados foi confirmada pelo teste de Cochran. O Limite de Detecção (LD) para cada um dos dois métodos de extração utilizados variou de 0,06 a 0,50 ng L(-1) para o SPE e 0,01 a 0,12 ng L(-1) para o ASE. A repetibilidade, expressa através dos coeficientes de variação (CV), apresentou valores inferiores a 20 por cento. A recuperação média dos analitos variou de 60 por cento a 118 por cento quando da extração em fase sólida (SPE) e de 65 a 106 por cento para o material particulado suspenso. A seletividade do método foi avaliada pelo Teste F (Snedecor) de homogeneidade de variâncias e pelo Teste t (Student) de comparação de médias. Possíveis perdas durante o processo foram monitoradas pelo uso do padrão surrogate e encontraram-se em limites aceitáveis. O método validado foi aplicado para a análise da água do Canal do Mangue, região central do Rio de Janeiro, e o intervalo encontrado para o somatório de PCBs totais variou de 2,17 ng L(-1) a 5,29 ng L(-1).
The aim of this work consists of the implementation and validation of a methodology for determination of polychlorinated biphenyls (PCBs) in water samples and particulate matter by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). The surface water analysis method was developed for the simultaneous determination of 41 PCBs; using the Solvent Accelerated Extraction (ASE) for the suspended particulate matter and the Solid Phase Extraction (SPE) for the dissolved fraction. Quantification was performed in Selective Reaction Monitoring (SRM) mode, with monitoring of two m/z precursor-product fragmentation patterns. The linearity of the analytical curves was confirmed by the coefficient of determination (R2), the random behavior of the residual plots and by the F test in the analysis of variance (ANOVA) for the regression. The homoscedasticity of the data was confirmed by the Cochran test. The limit of detection (LD) for each one of the two extraction methods used vary in a range of 0.06 to 0.50 ng L(-1) for the SPE and 0.01 to 0.12 ng L(-1) for the ASE. Regarding the repeatability studies, the coefficients of variation (CV) found were less than 20 per cent. The average recovery of the analytes ranged from 60 per cent to 118 per cent on Solid Phase Extraction (SPE) and from 65 to 106 per cent for the suspended particulate matter. The Method selectivity was evaluated by the F (Snedecor) test of homogeneity of variances and by the t-Test (Student) of means comparison. Possible losses during the process were monitored by using surrogate standards that were within acceptable limits. The validated method was further applied to analyze the surface water of Mangue Canal, central region of Rio de Janeiro, and the sum of total PCBs ranged from 2.17 ng L(-1) to 5.29 ng L(-1).
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Freitas, Andrew Daniel Sanchez. "Method Development for the Synthesis of Anaerobic Digester Biogas with the Laboratory Environment." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/51388.
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Biogas, a gaseous mixture produced during decomposition of organic matter, is a renewable, easily generated and common byproduct of anaerobic digestion at wastewater treatment plants (WWTP), landfills and agricultural operations. There is growing interest in researching and utilizing the energy potential associated with its combustion. Siloxanes, a family of volatile organic silicon compounds, pose large impediments to biogas usage due to the formation and precipitation of silicon dioxide within combustion devices. Removal of siloxanes prior to combustion is therefore a growing endeavor. Research was performed to synthesize a representative gas stream produced from anaerobic digesters within WWTP. Methane, carbon dioxide and hydrogen sulfide were combined with humidity and gaseous siloxane in levels characteristically seen exiting anaerobic digesters. A methanol impinger train was utilized to sample the biogas composite. Gas chromatography-mass spectrometry (GC-MS) was used to determine gas-phase siloxane concentrations in the gas stream effluent for the purposes of confirming the generation of a consistent and reproducible biogas stream.Master of Science
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Aldaeus, Fredrik. "New Tools for Trapping and Separation in Gas Chromatography and Dielectrophoresis : Improved Performance by Aid of Computer Simulation." Doctoral thesis, Stockholm : Department of Analytical Chemistry, Stockholm university, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7170.
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Yasin, Mohammed. "Environmental monitoring of pesticides in components of river systems - method development and analysis by gas chromatography negative-ion chemical ionization mass spectrometry." Thesis, University of Salford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308379.
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Adam, Hassan Ali. "A solid phase microextraction/gas chromatography method for estimating the concentrations of chlorpyrifos, endosulphan-alpha, edosulphan-beta and endosulphan sulphate in water." Thesis, Peninsula Technikon, 2003. http://hdl.handle.net/20.500.11838/899.
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Thesis (MTech (Chemical Engineering))--Peninsula Technikon, Cape Town, 2003The monitoring of pesticide contamination in surface and groundwater is an essential aspect of an assessment of the potential environmental and health impacts of widespread pesticide use. Previous research in three Western Cape farming areas found consistent (37% to 69% of samples) pesticide contamination of rural water sources. However, despite the need, monitoring of pesticides in water is not done due to lack of analytical capacity and the cost of analysis in South Africa. The Solid Phase Microextraction (SPME) sampling method has been developed over the last decade as a replacement for solvent-based analyte extraction procedures. The method utilizes a short, thin, solid rod of fused silica coated with an absorbent polymer. The fibre is exposed to the pesticide contaminated water sample under vigorous agitation. The pesticide is absorbed into the polymer coating; the mass absorbed depends on the partition coefficient of the pesticide between the sample phase and the polymeric coating, the exposure time and factors such as agitation rate, the diffusivity of the analyte in water and the polymeric coating, and the volume and thickness of the coating. After absorption, the fibre is directly inserted into the Gas Chromatograph (GC) injection port for analysis. For extraction from a stirred solution a fibre will have a boundary region where the solution moves slowly near the fibre surface and faster further away until the analyte is practically perfectly mixed in the bulk solution by convection. The boundary region may be modelled as a layer of stationary solution surrounded by perfectly mixed solution.
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Rodriguez, Frausto Heriberto. "Development and analytical validation of a gas chromatography-mass spectrometry method for the assessment of gastrointestinal permeability and intestinal absorptive capacity in dogs." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3257.
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Incardona, Marie-Françoise. "Mesure de lésions de type oxydatif de l'ADN dans les fluides biologiques et dans l'ADN isolé." Grenoble 1, 1994. http://www.theses.fr/1994GRE10162.
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Divers facteurs (stress oxydant, exposition a divers rayonnements) peuvent engendrer des modifications des bases de l'adn. La mise au point de methodes d'analyse suffisamment fiables et sensibles nous a permis de detecter et de doser plusieurs dommages oxydatifs dans un fluide biologique (urine humaine) et dans l'adn isole. Pour cela, deux techniques ont ete respectivement mises en uvre: la chromatographie gazeuse couplee a la spectrometrie de masse (cg/sm) et la chromatographie liquide a haute performance associee a une detection electrochimique (clhp/ec). La mise au point de methodes de detection de dommages oxydatifs dans l'urine par cg/sm a ete appliquee a la 5-hydroxymethyluracile, la 5-hydroxyuracile et a leurs nucleosides. Ce travail a implique, la synthese d'etalons internes enrichis isotopiquement (#2h, #1#5n, #1#8o) pour une mesure quantitative des lesions, la mise au point de la technique d'extraction du defaut et enfin l'optimisation des parametres de cg/sm pour l'obtention d'une reponse optimale. Un deuxieme volet du travail a concerne le developpement d'une nouvelle methode d'analyse de bases modifiees utilisant une colonne chromatographique a phase normale (nh#2) couplee a un detecteur electrochimique. Celle-ci nous a permis de detecter plusieurs molecules hydrophiles (5-hydroxyuracile, 5-hydroxycytosine, 2,6-diamino-4-hydroxy-5-formamidopyrimidine et 4,6-diamino-5-formamidopyrimidine) jusqu'a present difficiles a mesurer dans les conditions usuelles (colonne c18). Nous avons applique cet outil a la recherche et au dosage de la 5-hydroxyuracile et de la 5-hydroxycytosine dans l'adn soumis a deux conditions de stress oxydant (radiations ionisantes et photooxydation sensibilisee). La recherche de ces bases oxydees dans l'adn a ete facilitee par une nouvelle methode d'hydrolyse
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Jejdling, Julia. "Biomonitoring of soil remediation workers´ exposure to polycyclic aromatic compounds (PACs) – method development and characterisation of PACs in blood." Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-74387.
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For a long period of time, it has been common to use creosote for impregnation of railroad ties. Creosote consists of 85% polycyclic aromatic hydrocarbons (PAHs), of which some are carcinogenic and/or mutagenic. In 2016, a soil remediation process was commenced at an old impregnation facility in Sweden and both dermal, urine and blood samples were taken from soil remediation workers to investigate the occupational exposure. The objectives of this study were to develop a method for the extraction of polycyclic aromatic compounds (PACs), including PAHs, oxy-PAHs, alkylated PAHs and dibenzothiophenes and azaarenes from blood, and to quantify PAHs in the collected blood samples from the soil remediation workers. In the method development, two parameters were tested: centrifugation of samples before extraction and use of either basic or deactivated silica in the clean-up step of the blood extracts. The results showed that the best method was without centrifugation and with use of basic silica. Results from the analysis of the soil remediation workers´ blood showed PAHs in average concentrations of 0.05-6.47 ng/mL blood, with fluorene and biphenyl being the most abundant PAHs. The occupational groups (office, machine and sampling) had similar average concentrations of PAHs, with office workers being slightly less exposed. The PAHs blood profile did not reflect the PAHs profiles in contaminated soil from the area; the blood profiles had relatively higher abundances of low molecular weight PAHs, while the soils had higher relative concentrations of middle molecular weight PAHs. Both blood and soils had low relative concentrations of high molecular weight PAHs. Pyrene concentrations in blood and 1-hydroxypyrene metabolite concentrations in urine samples showed no correlation (linearity r2=0.045). Both blood and urine samples from the workers indicated a low exposure of PAHs. The method tested in this study can be used for analysis of a broad range of PACs and seems to be a better approach for studying the exposure of PACs than today’s methods analysing a few urine metabolites. But additional clean-up is suggested to improve the quantification of all blood samples. Further investigations are required to gain an understanding of normal, unexposed PACs levels in blood.
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Seno, Hiroshi, Osamu Suzuki, Akira Ishii, Kei Zaitsu, Hideki Hattori, Tadashi Ogawa, and Masae Iwai. "SIMPLE AND RAPID ASSAY METHOD FOR SIMULTANEOUS QUANTIFICATION OF URINARY NICOTINE AND COTININE USING MICRO-EXTRACTION BY PACKED SORBENT AND GAS CHROMATOGRAPHY-MASS SPECTROMETRY." Nagoya University School of Medicine, 2013. http://hdl.handle.net/2237/18475.
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Slabizki, Petra [Verfasser], and Hans-Georg [Akademischer Betreuer] Schmarr. "Identification and quantification of cork off-flavor compounds in natural cork stoppers by multidimensional gas chromatographic methods / Petra Slabizki. Betreuer: Hans-Georg Schmarr." Duisburg, 2016. http://d-nb.info/1101343516/34.
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LACHTER, DANIELA RODITI. "DEVELOPMENT AND VALIDATION OF A METHOD FOR PESTICIDE ANALYSIS IN FOOD PRODUCE FROM THE STATE OF RIO DE JANEIRO USING GAS CHROMATOGRAPHY WITH TANDEM MASS SPECTROMETRY." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2017. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=37039@1.
Full textAbstract:
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
PROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
O presente trabalho envolve a implementação e validação de metodologia analítica para determinação de resíduos de agrotóxicos em amostras de alimentos provenientes do Estado do Rio de Janeiro, cujos resultados servirão para um aumento de informações de um banco de dados sobre os mesmos, bem como para o aprimoramento do sistema nacional de saúde e promoção da saúde da população. Foram analisados os agrotóxicos das classes nitrogenados e piretróides. As amostras foram coletadas no CEASA da cidade do Rio de Janeiro, uma vez que este é o principal centro distribuidor de frutas e hortaliças da cidade. As culturas escolhidas para análise foram maçã, manga, morango, pepino e tomate de mesa. Após a otimização das condições cromatográficas, metodologia de extração e validação da metodologia pelos parâmetros de curva analítica e linearidade, seletividade (efeito matriz), repetibilidade, recuperação, homocedasticidade e limite de detecção do método, as amostras foram coletadas e analisadas no período de novembro de 2016 a fevereiro de 2017. A análise foi baseada no método QuEChERS e quantificação por cromatografia gasosa acoplada a espectrometria de massas tandem, no modo de Monitoramento de Múltiplas Reações. Obteve-se um método de curta duração, inferior a vinte minutos, capaz de quantificar 41 agrotóxicos com dois monitoramentos precursor-produto para cada um dos analitos, apresentando as seguintes vantagens: rápido, econômico, fácil, efetivo, robusto e seguro. O LDM variou de 1,34 a 10,22 ng g(-1). A concentração de agrotóxicos das amostras esteve abaixo desses valores para a maioria (78 porcento dos casos) dos 41 agrotóxicos analisados. Para as culturas de tomate e pepino, os agrotóxicos quantificados estiveram próximos aos seus respectivos limites de detecção. Para a manga, observaram-se alguns picos de maior concentração para o propargito e lambda-cialotrina. O primeiro de uso não autorizado pela ANVISA e o segundo, embora presente, abaixo do limite estabelecido por esta agência. As culturas de maçã e morango apresentaram a maior contaminação por agrotóxicos (38 e 44 porcento acima do LDM, respectivamente), muitos não autorizados pela ANVISA. Por ser um centro de grande distribuição de alimentos, a CEASA é suprida por diferentes fornecedores, sendo assim a variabilidade das fontes de alimentos coletados é muito grande e, portanto, a continuidade desta sistemática de avaliação torna-se necessária.
The present work regards the implementation and validation of a method for analysis of pesticide residues in produce from the state of Rio de Janeiro for the improvement of the national health system. Pyrethroids and triazines class pesticides were analyzed for this research. The samples were collected at CEASA in the city of Rio de Janeiro, since it is the main fruit and vegetable distribution center in the city. The produce chosen for the analyses were apple, mango, strawberry, cucumber and tomato. After optimization of the chromatographic conditions, extraction methodology and evaluation of the parameters linearity, selectivity (matrix effect), repeatability, recovery, homocedasticity and limits of detection of the method, the samples were collected, from November 2016 to February 2017. The QuEChERS method was used for the extraction of pesticide residues and the PSA method was used for the purification of extracts, both in triplicates. The extracts were analyzed by gas chromatography with tandem mass spectrometry in Selected Reaction Monitoring mode (Multiple Reaction Monitoring). A short run method was achieved for the determination of 41 pesticides with two precursor-product for each analyte. The analitycal method showed several advantages - quick, cheap, easy, effective, rugged and safe. The detection limits were 1,34 ng/g and 10,22 ng/g. The majority of the pesticides analysed (78 per cent) were below this result. For tomato and cucumber, the only quantified compounds were close to their respective detection limits. For the analysis of mango pesticides, some peaks of higher concentration for propargite and lambda-cyhalothrin were observed. The first one is not authorized by ANVISA and the second, although present, was found below the limit established by this agency. The apple and strawberry crops showed the highest contamination by pesticides (38 and 444 per cent, respectively), many of which were not authorized by ANVISA. CEASA is a large food distribution center, so it is supplied by different distributers. The variability of the sources of food collected is very large. A more representative study on the quality of food would require a higher number of samples with a higher frequency of sampling.