Dissertations / Theses: 'Hyphenated technique'

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Harris, Dee. "Design and development of a hyphenated technique for monitoring the cure of epoxy-amine resin systems." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/2872/.

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The main focus of the current study was to design, construct and evaluate a common platform to enable the integration of multiple sensing systems for cure monitoring. An Abbe refractometer was selected to house a custom-made cell which accommodated the following optical sensors: (i) Fresnel reflection sensor; (ii) near-infrared transmission sensor; (iii) evanescent wave sensor; and (iv) fibre Bragg grating sensor. The cell was designed such that it was also possible to simultaneously acquire conventional refractive index data during the cross-linking process. Thus, the cross-correlation of data on refractive index, cross-linking kinetics, strain and temperature was facilitated. It was found that the trends observed in the qualitative (intensity-based refractive index monitoring via the Fresnel reflection sensor) and quantitative (optical fibre-based transmission FTIR spectroscopy) approaches were similar during the cure of common thermosetting resin systems. Furthermore, for the first time, S-2 glass® fibres were used to obtain evanescent wave spectra during cross-linking, and excellent correlation was observed with the transmission FTIR spectral data. Fibre Bragg grating sensors were used to infer the magnitude of the residual fabrication strain. Excellent correlation was observed between the refractive index data generated using the Abbe refractometer and Fresnel reflection sensor.

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Fedrizzi, Bruno. "Identification, quantitation and origin of sulfur compounds in grape products. An approach via hyphenated mass spectrometry techniques." Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3426543.

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The contribute of the Analytical Chemistry in the study of complex matrices, as for instance foodstuff, is crucial. In particular the development of chromatographic methods allows to quantify important technological, microbiological and physiological markers. The ensemble of all these information furthers a deeper and higher knowledge. This Ph.D. project was designed to define the tools and evaluate the contribution of an important class of molecule on wine aroma. Grape products are really important in the cultural and dietary Italian traditions; moreover Italy is both the first producer and the first consumer around the world. Oenological products have been largely studied since the early ’70, even if the lack of biochemical and microbiological knowledge and the poor sensitivity of the analytical techniques did not allow to carry an deep study on sulfur compounds. This project, planned to bid analytical and oenological chemistry, focussed its attention on the study of sulfur compounds. Dealing with complex matrices, the first problem we had to face was the matrix effects. The overcoming of such issue or the attempts in reducing it, costs to chemical laboratory, wasting of time and money to prepare suitable internal standards. In this thesis we proposed a statistical approach based on the variance component model able to handle matrix effects. The benefits obtained by this approach definitely outweigh both the slightly worse sensitivity and uncertainty. Another topic discussed in the thesis is the definition of analytical methods to quantify sulfur compounds. This subject has been studied distinguishing sulfur compounds into two sub-groups: o fermentative sulfur compounds: molecules produced by yeast metabolisms from amino acidic precursors. o varietal sulfur compounds: molecules present in specific variety, as conjugated with cysteine and glutathione. The free forms, which are sensorially active, are released during fermentation by means of a specific enzymatic activity. This further classification was kept in the development of the analytical methods because the two classes required different sensitivity as well as metabolomics study were separated. Concerning fermentative sulfur compounds a HS-SPME/GC-MS method was optimised and validated. With this method a wide range of sulfur compounds were quantified. Such tool was applied to metabolomic studies, concerning the influence of variety, ageing, yeast strain and other technological practice on the level of 13 fermentative sulfur compounds. The results obtained from the development of the analytical method permitted to highlight the potentiality of the HS-SPME technique in sampling volatile compounds in complex matrices. This approach allows an easier and safer lab conditions, avoiding the use of organic solvents. The metabolomic studies furnished important suggestion on the influence of important oenological variables on the level of important sulfur compounds. The last topic discussed in this thesis concerns the study of varietal sulfur compounds. The lack of suitable analytical technique, sufficiently rapid and avoiding the use of mercuro-organic compounds stimulated our research in verifying the performance of headspace technique in extracting these analytes. We optimised and validated HS-SPME and purge and trap methods and finally we defined a non-parametric robust approach to compare performances from different analytical methods. Owing to the recent interest of the scientific research in trying to understand the formation and evolution of varietal sulfur compounds, we focussed our attention on their precursors. The first step was the synthesis of the putative precursors, followed by the optimisation of LC-MS/MS methods to quantify them. It was possible to identify a new precursor by LC-MS/MS experiments. Finally, by the isolation of the enzyme potentially responsible of the biosynthesis of the varietal thiols precursors, we gave a preliminary explanation of the formation of these glutathionylated precursors during grape ripening. By this project it has been possible to study and apply the newest analytical techniques available and it has been possible to define statistical procedures to overcome the most common issues in studying complex matrices. Furthermore it was clarified the contribution of an important class of molecules, such as sullfur compounds, on oenological matrices. Il contributo della Chimica Analitica nello studio delle matrici complesse, quali ad esempio quelle alimentari, è cruciale. In particolare lo sviluppo di metodi cromatografici avanzati può permettere di dosare importanti marker tecnologici, microbiologici e fisiologici e quindi consentire un approfondimento delle attuali conoscenze. Questo lavoro è stato concepito allo scopo di definire gli strumenti per valutare il contributo di un’importante classe di molecole all’aroma dei vini. Il vino riveste un ruolo di primaria importanza nelle tradizioni culturali ed alimentari Italiane, inoltre l’Italia risulta primo produttore e primo consumatore mondiale di vino. I prodotti enologici sono stati largamente studiati fin dai primi anni ’70, anche se l’assenza di conoscenze biochimiche e microbiologiche e la mancanza di tecniche analitiche sufficientemente sensibili non ha consentito lo studio esaustivo della classe dei composti solforati. Questa tesi, nata da esigenze legate alla chimica analitica e alla chimica enologica, ha avuto come punto centrale lo studio dei composti solforati nei vini. Il primo problema che si è dovuto affrontare nello studio di matrici complesse come quelle enologiche è stato quello relativo agli effetti matrice. Il superamento o il contenimento di questo problema crea ogni giorno costi in termini di tempo e di preparazione di opportuni standard interni. In questa tesi si è proposto un metodo statistico basato sul modello a componente di varianza in grado di gestire questo problema. I vantaggi sono notevoli, a fronte di una incertezza leggermente maggiore e di una sensibilità di poco peggiorata. Altro argomento trattato è stata la definizione dei metodi analitici in grado di quantificare e quindi di studiare i composti solforati. Questa materia è stata affrontata riconoscendo una prima distinzione all’interno del gruppo degli analiti indagati: o composti solforati fermentativi: molecole derivanti dal metabolismo del lievito a partire da precursori amminoacidici o composti solforati varietali: molecole presenti in specifiche varietà come coniugati della cisteina e del glutatione e rilasciati durante la fermentazione alcolica ad opera di specifiche attività enzimatiche. Questa suddivisione è stata mantenuta anche nello sviluppo dei metodi analitici, in quanto sensibilità richieste e conseguenze metabolomiche erano anch’esse distinte. Per quanto riguarda i composti solforati fermentativi, durante il dottorato di ricerca è stato ottimizzato e validato un metodo HS-SPME/GC-MS per l’analisi di un’ampia gamma di molecole tipicamente derivanti dal metabolismo del lievito. Tale approccio è poi stato la base per studi di natura più squisitamente metabolomica in cui è stato verificato come il cultivar (i.e. la varietà), l’invecchiamento, il ceppo di lievito e altre pratiche tecnologiche potessero influenze il livello e l’evoluzione degli analiti indagati. I risultati ottenuti per quanto attiene lo sviluppo del metodo in spettrometria di massa hanno potuto confermare con la tecnica SPME con campionamento in spazio di testa sia una tecnica di elezione per l’analisi di molecole volatili. Inoltre questo approccio consente una gestione semplice ed enviromental friendly in confronto con i più obsoleti metodi di estrazione con solvente. Gli studi metabolomici hanno consentito di trarre importanti considerazioni su aspetti molto importanti nella definizione della qualità del prodotto finale. Tali risultati consentono anche una trasferibilità nei settori della ricerca applicata e dell’enologia. Come ultima classe di analiti indagati si sono studiati i composti solforati varietali. L’assenza di metodi sensibili e sufficientemente rapidi da essere applicati per studi su un numero significativo di campioni ha spinto la nostra attenzione alla verifica delle potenzialità delle tecniche in spazio di testa nel dosare queste molecole. Si sono ottimizzati e validati metodi HS-SPME e purge and trap ed è stata definita una procedura non parametrica robusta per il confronto delle performance delle diverse procedure. Visto il recente interesse della ricerca scientifica operante nel settore al controllo della formazione ed evoluzione di queste molecole, abbiamo focalizzato la nostra attenzione sui precursori dei composti solforati varietali. Il primo stadio è stata la sintesi di queste molecole, seguito poi dall’ottimizzazione di metodi LC-MS/MS per il dosaggio di queste molecole. In questo contesto è stato possibile identificare per la prima volta un nuovo potenziale precursore di aroma, tramite esperimenti LC-MS/MS. Da ultimo, attraverso l’isolamento dell’enzima responsabile della biosintesi dei precursori d’aroma è stato possibile proporre una preliminare spiegazione alla formazione di tali molecole durante la maturazione della materia prima. In conclusione, grazie a questa tesi di dottorato, è stato possibile approfondire ed applicare alcune delle più moderne tecniche analitiche a disposizione, è stato possibile definire procedure statistiche per superare i più comuni ostacoli nello studio di matrici complesse, ed è stato possibile chiarire il contributo di una classe importante di molecole come i composti solforati nelle matrici enologiche.

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Homazava, Nadzeya. "Development of a novel microflow-capillary technique online hyphenated to the inductively coupled plasma mass spectrometry for the spatial- and time-resolved investigation of local corrosion /." [S.l.] : [s.n.], 2009. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000288126.

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Wang, Tongwen. "Hyphenated HPLC-MS technique for analysis of compositional monosaccharides of transgenic corn glycoprotein and characterization of degradation products of diazinon, fonofos and aldicarb in various oxidation systems." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.mst.edu/thesis/pdf/WangTongwen_09007dcc804e975c.pdf.

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Thesis (Ph. D.)--University of Missouri--Rolla, 2007. Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 23, 2008) Includes bibliographical references.

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Jordan, Sheri Lynne. "Hyphenated fourier transform infrared spectrometry : techniques for separations and analysis /." Diss., This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-08282003-155254/.

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Kapoore, Rahul Vijay. "Mass spectrometry based hyphenated techniques for microalgal and mammalian metabolomics." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/8234/.

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In metabolomics, the analytical challenge is to capture the chemical diversity of the metabolome. With the current technologies only a portion of the metabolome can be analysed. As a result there is a drive to direct significant analytical efforts towards capturing the metabolome or changes in the metabolome reliably and reproducibly in biological systems. Apart from analytical challenges, the challenges also include development of appropriate methodologies to quench and extract metabolites which is a crucial parameter in sample preparation and is required to achieve an accurate representation of phenotype. This thesis focuses on addressing both the challenges in mammalian and microalgal metabolomics. Metabolomics in cancer research is gaining momentum as a tool to understand the molecular mechanism of disease progression and for the identification of specific biomarkers which may assist distinguishing between normal, benign and metastatic cancer states. In our first investigation we developed GC-MS based modified direct cell scraping, bead harvesting and LN2 methods for harvesting three adherently grown mammalian cell lines (two breast cancer cell lines MDA-MB 436, MCF7 and an endothelial cell line HMEC1) which provided rapid and reliable route with three fold improved metabolome coverage and reduced the artifacts due to metabolome leakage compared to conventional methods. Later optimized treatments were employed and the influence of various washing and quenching solvents (buffered/unbuffered) on metabolite leakage was investigated for metastatic cancer cell line MDA-MB-231. This identified one washing step with PBS followed by quenching with 60% methanol (buffered with HEPES) as the best washing and quenching solvents. Further validation and comparison of proposed workflows for metabolomic study of two metastatic TNBC cell lines (MDA-MB-231 and MDA-MB-436) resulted in recovery of 154 unique metabolites and demonstrated the robustness and reliability of these methods in pathway based analysis in cancer. In case of GC-MS based microalgal metabolomics, with comprehensive evaluation of selected quenching and extraction methods in model microalga C. reinhardtii, we have successfully demonstrated that the choice of quenching and extraction solvents have significant impact on recovery of different classes of metabolites. Our results clearly indicate that 60% methanol (buffered with HEPES) and 25 % aqueous methanol are the best suited quenching and extraction solvent respectively for untargeted metabolomic analysis of C. reinhardtii, as the highest number of metabolites belonging to various chemical classes were recovered with good intensities and reproducibilities with this miniaturized proposed method compared to other evaluated methods. Later impact of various stages involved in biodiesel production workflow from microalga on recovery of biodiesel was assessed in three microalgal species namely C. reinhardtii, D. salina and N. salina. Within which we have developed an optimized GC-FID method and miniaturized direct TE method for quantification of fatty acids, which can be applied to a small amount of biomass and saves tremendous amounts of time, solvents and reagents required, is less expensive and uses environment friendly solvents making it more suitable for sustainable large scale production. In our final investigation, we directed our efforts towards preliminary optimization and comparative analysis of HILIC and IP-RP-HPLC based separation for the retention and separation of specific metabolites classes. This identified HILIC as the best available column till date for untargeted metabolomic studies. The descriptive understanding gained from each of these investigations provides greater insight into biology of mammalian and algal systems by improving the metabolome coverage for various metabolite classes. These insights illustrating the underlying molecular pathways involved in respective biology's, will help scientific communities in identifying as-of-yet-missing reactions in the metabolic network. In addition these insights will surely help in generating many hypothesis based investigations in microalgal and cancer community.

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Bailey, Nigel John Collingwood. "Development and application of hyphenated NMR techniques to the study of agrochemical metabolism." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394243.

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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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Williams, Samuel Thomas. "Analysis of erythropoietin for anti-doping purposes with a focus on hyphenated techniques." Thesis, King's College London (University of London), 2014. https://kclpure.kcl.ac.uk/portal/en/theses/analysis-of-erythropoietin-for-antidoping-purposes-with-a-focus-on-hyphenated-techniques(8b6d26e7-a9c5-4d5a-9e3a-f32be79939e2).html.

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To improve detection of the misuse of erythropoietin (EPO) for performance enhancing purposes, this PhD examined ways to improve recovery and preanalysis concentration of EPO from urine. It also looked at ways to enhance the signal in liquid chromatography tandem mass spectrometry of the acidic glycopeptides from digested EPO, and at distinguishing between recombinant EPO and human urinary EPO based on differences in their glycosylation. Due to a shortage of supply of available analytical standards, model glycoproteins were frequently used in place of endogenous EPO. Immunoextraction with magnetic beads effectively recovered EPO from urine which had been filtered to remove large proteins, but was unsuccessful from unfiltered urine, suggesting more research into the right choice of antibody was needed. The specific and reversible binding of boronic acids to cis-diol groups found in the glycan groups of glycoproteins was investigated as a device for the selective binding of EPO. Attempts were made to functionalise mesoporous silica for use as a column packing material. Although there was evidence that at least one method of functionalisation was successful, the use of this silica to extract glycoproteins and glycopeptides was not. Signal enhancement through the introduction of ‘superchargers’ into LC solvents was investigated. This was effective with small molecules, and also improved detection of sialylated glycopeptides. The results do not fit entirely with current models of how superchargers exert their effect, suggesting they are incomplete. Finally, the cleavage, digestion and derivatisation of N-glycans to identify bisected and non-bisected structures as a way to discriminate between rEPO and huEPO was examined. Samples were analysed using LC-MS and CE-LIF, and although much of the work was carried out using a model glycoprotein, there is some evidence that the approach may be capable of discriminating between artificial and endogenous EPO at the levels found in anti-doping samples.

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Prazen, Bryan J. "Development of high speed hyphenated chromatographic analyzers and second order data analysis techniques /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/11550.

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LUPI, FRANCESCA. "Fungal populations and metabolism of fusarium mycotoxins in cereals: from occurrence to analysis by hyphenated analytical techniques." Doctoral thesis, Università di Foggia, 2017. http://hdl.handle.net/11369/361931.

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Il successo nella produzione di cereali, per quanto riguarda la contaminazione fungina durante la fase pre-raccolta, è fortemente correlato alla valutazione del controllo qualità. Lo scopo di questa ricerca è stato quello di studiare come lo zearalenone (ZEN), un metabolita secondario prodotto da diverse specie di Fusarium, sia metabolizzato e modificato nei cereali, come ad esempio il grano e l’orzo. Inoltre, abbiamo sviluppato e ottimizzato metodi analitici per l’identificazione di composti organici volatili (VOC) prodotti dall’interazione tra due specie fungine tossigene selezionate (F. graminearum e F. culmorum) e piante di frumento. L’identificazione di biomarcatori di infezione precoce, all’interno di questi VOC, può contribuire a prevenire/ridurre le contaminazioni all’interno della catena alimentare. Per quanto riguarda la micotossina ZEN, sono stati eseguiti esperimenti “Time Course”. Il grano e l’orzo sono stati trattati con ZEN. I campioni sono stati raccolti in tempi differenti e analizzati con un sistema UHPLC accoppiato ad uno spettrometro di massa QTOF. Il metodo LC-MS è stato ottimizzato per consentire un’analisi veloce, ma comunque in grado di separare i metaboliti target. Per quanto riguarda i composti volatili, le piante di frumento sono state inoculate utilizzando sospensioni di spore dei due funghi selezionati. Le analisi sono state effettuate in differenti fasi fenologiche di crescita. I VOC sono stati campionati direttamente nello spazio di testa di foglie e spighe, mediante microestrazione in fase solida, e analizzati mediante strumentazione GC-MS. Quantità assolute di ZEN e dei suoi metaboliti possono essere riportati rispetto al tempo di raccolta dopo il trattamento. Sulla base del recupero percentuale rispetto al punto zero, si è visto che la maggioranza dello ZEN non è stata metabolizzata dalle piante. I principali prodotti di metabolizzazione sono stati i glucosidi. Invece i dati ottenuti dalle analisi dei VOC sono stati elaborati utilizzando approcci statistici, come la PCA (analisi dei componenti principali), che sottolineano differenze molto importanti tra i campioni. In particolare la maggior parte dei VOC sono stati rilevati durante la maturazione lattea. Tra le sostanze identificate, alcoli alifatici, aldeidi e chetoni sono stati i più abbondanti. Questi composti hanno differenti vie di biosintesi. Per quanto riguarda gli esperimenti “Time Course”, è possibile concludere che la maggior parte dello ZEN rimane non metabolizzata, però abbiamo osservato alcuni glucosidi, in particolare nell’orzo, il quale si è dimostrato più attivo nella produzione di glucosidi rispetto al grano. L’approccio sviluppato nello studio dei volatili ha fornito risultati promettenti nel prevedere il potenziale della formazione della tossina, individuando la presenza di entrambe le specie di Fusarium nelle fasi iniziali della crescita fungina nelle cultivar di frumento.

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Eyres, Graham Terence, and n/a. "Determination of character-impact odorants in hop essential oils using hyphenated techniques in gas chromatography." University of Otago. Department of Food Science, 2007. http://adt.otago.ac.nz./public/adt-NZDU20080125.143442.

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Hops (Humulus lupulus L.) are an indispensable component of beer, with the essential oil responsible for imparting distinctive odour and aroma characteristics to beer. However, not all character-impact odorants in hop essential oil have been identified and hop aroma in beer is still not completely understood. The composition of hop essential oil is very complex with 485 compounds currently identified in the literature, and recent research suggests that up to 1000 compounds may actually be present. Only a certain number will be present at concentrations above threshold and make a direct contribution to the odour of the oil. In addition, many important odorants are only present at trace concentrations. Gas chromatography-olfactometry (GC-O) using human assessors is the best way to locate potent odorants and facilitate their identification. A novel methodology was developed to identify the character-impact odorants in hop essential oil samples using hyphenated techniques in gas chromatography. GC-O was used to locate odour active compounds and determine relative importance using CharmAnalysis[TM] according to the odour potency principle. Due to the chemical complexity of the samples, considerable co-elution of peaks occurs during single column gas chromatography (1DGC), making the detection and identification of character-impact odorants challenging. Therefore, comprehensive two-dimensional gas chromatography (GCxGC) combined with time-of-flight mass spectrometry (TOFMS) was used to resolve and identify compounds eluting in the odour active regions. The methodology was developed in a case study on coriander (Coriandrum sativum) and wild coriander (Eryngium foetidum) leaf essential oils. During GC-O analysis of these samples it was recognised that odour active regions frequently coincide with several co-eluting compounds. To address this, a heart-cut multidimensional gas chromatography-olfactometry (MDGC-O) instrument was developed to resolve these 'co-eluting odour clusters' and determine the compound(s) responsible for the odour perception. The 'spicy' character of hops is considered to be a desirable attribute in beer associated with 'noble hop aroma'. However, the compounds responsible have yet to be adequately elucidated. This character was investigated using a commercial 'Spicy' fraction of hop essential oil, selectively enriched for monoterpene and sesquiterpene alcohols. The odour active compounds in (i) the spicy fractions and (ii) the whole essential oils of four different hop varieties were compared using the presented methodology. A compound with an intense 'woody, cedarwood' odour was determined to be a potent, character-impact odorant in all samples. This odour coincided with a complex region of the chromatogram where up to thirteen compounds were co-eluting. The peak responsible for this odour was determined by (i) correlation of peak areas with odour potency (Charm) values and (ii) MDGC-O. The compound was tentatively identified by GCxGC-TOFMS as 14-hydroxy-β-caryophyllene, which has not previously been reported as an odorant in hop essential oil. It was concluded that this compound and other 'woody, cedarwood' odorants contributed to the 'spicy' character of the investigated hop samples. Compounds previously associated with noble hop aroma, notably caryophyllene oxide, humulene epoxides I and II, and humulenol II, did not contribute to the odour character of the hop samples. Other potent odorants that were identified in the whole essential oil and spicy fractions of hops were: geraniol, linalool, β-ionone, eugenol, isovaleric acid, and β-damascenone. While myrcene was a moderately potent odorant in the whole hop essential oil samples, the abundant sesquiterpene hydrocarbons α-humulene, β-caryophyllene and β-farnesene did not significantly contribute to the odour character.

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Vetere, Alessandro [Verfasser], and Wolfgang [Akademischer Betreuer] Schrader. "Development of hyphenated techniques for the analysis of complex mixtures / Alessandro Vetere ; Betreuer: Wolfgang Schrader." Duisburg, 2017. http://d-nb.info/1138922633/34.

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De, Goede Elana. "The development of analytical techniques for studying degradation in impact polypropylene copolymers." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1162.

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Thesis (DSc (Chemistry and Polymer Science))--University of Stellenbosch, 2009. Unstabilised polyolefins are susceptible to degradation when exposed to molecular oxygen, heat, irradiation as well as chemical and mechanical stimuli. Oxidation leads to changes in molecular properties such as molecular weight, molecular weight distribution, chemical composition, chemical composition distribution and crystallisability. Conventional analytical techniques are of limited use when studying the degradation of heterogeneous materials such as impact polypropylene copolymers (ICPP). These copolymers consist of a number of components of different monomer contents, isotacticity and crystallinity, ranging from amorphous EPR to highly crystalline polypropylene. The individual components are affected differently by degradation, leading to heterogeneity within the degradation of impact copolymers. Novel analytical approaches that acknowledge the heterogeneity in sample composition are needed to study the degradation behaviour of such heterogeneous materials. This study describes the combination of fractionation and hyphenated techniques with conventional analyses for extensive structural characterisation of complex impact copolymers as well as their degradation behaviour. Temperature rising elution fractionation (TREF) coupled to conventional techniques such as size exclusion chromatography (SEC), Fourier-Transform infrared spectroscopy (FTIR), Carbon-13 nuclear magnetic resonance (13C-NMR) and differential scanning calorimetry (DSC) indicated the ICPPs in question to consist of four main components, namely ethylene-propylene random copolymers (EPR), isotactic PP (iPP), as well as semi-crystalline ethylene-propylene copolymers (EPC) and lower isotacticity PP. The degradation of an ICPP was studied by a multi-component analysis procedure consisting of TREF coupled to SEC, 13C-NMR, as well as SEC-FTIR. Results obtained by this procedure indicated the change in crystallisability of the bulk sample observed by TREF, crystallisation analysis fractionation (CRYSTAF) and DSC to be the result of the preferential degradation of the iPP phase. Degradation of ICPPs initiates within this phase where chain scission and carbonyl group insertion leads to a change in the crystallisability of iPP chains. During TREF of degraded bulk ICPPs, the degraded iPP molecules elute at lower elution temperatures, depending on their degree of degradation. The other components of the copolymer were degraded to a lesser extent. Degradation products were also found to be heterogeneously distributed across the molecular weight distribution of each fraction, with a higher concentration appearing at the low molecular weight side. The multi-component analysis procedure was also used to study the difference in degradation behaviour between ICPPs of different comonomer content, isotacticity and crystallinity. The spatial heterogeneity of degradation within ICPPs was studied by Fourier-Transform infrared microspectroscopy (FTIR-μS). A heterogeneous distribution of degradation products was found across the depth of thicker sample specimens. These results were compared to those obtained by conventional layer-by-layer milling followed by SEC, FTIR and CRYSTAF. The principles of degradation within thick samples were similar to that observed for thin films, although additional contributions by sample morphology and oxygen diffusion were detected.

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Tollbäck, Petter. "Large Volume Injection and Hyphenated Techniques for Gas Chromatographic Determination of PBDEs and Carbazoles in Air." Doctoral thesis, Stockholm University, Department of Analytical Chemistry, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-367.

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This thesis is based on studies in which the suitability of various gas chromatography (GC) injection techniques was examined for the determination of polybrominated diphenyl ethers (PBDEs) and carbazoles, two groups of compounds that are thermally labile and/or have high boiling-points. For such substances, it is essential to introduce the samples into the GC system in an appropriate way to avoid degradation and other potential problems. In addition, different types of gas chromatographic column system and mass spectrometric detectors were evaluated for the determination of PBDEs.Conventional injectors, such as splitless, on-column and programmed temperature vaporizing (PTV) injectors were evaluated and optimized for determination of PBDEs. The results show on-column injection to be the best option, providing low discrimination and high precision. The splitless injector is commonly used for “dirty” samples. However, it is not suitable for determination of the high molecular weight congeners, since it tends to discriminate against them and promote their degradation, leading to poor precision and accuracy. The PTV injector appears to be a more suitable alternative. The use of liners reduces problems associated with potential interferents such as polar compounds and lipids and compared to the hot splitless injector, it provides gentler solvent evaporation, due to its temperature programming feature, leading to low discrimination and variance.Increasing the injection volume from the conventional 1-3 µL to >50 µL offers two main benefits. Firstly, the overall detection and quantification limits are decreased, since the entire sample extract can be injected into the GC system. Secondly, large volume injections enable hyphenation of preceding techniques such as liquid chromatography (LC), solid phase extraction and other kinds of extraction. Large-volume injections were utilized and optimized in the studies included in this thesis.With a loop-type injector/interface large sample volumes can be injected on-column providing low risk of discrimination against compounds with low volatility. This injector was used for the determination of PBDEs in air and as an interface for the determination of carbazoles by LC-GC. Peak distortion is a frequently encountered problem associated with this type of injector that was addressed and solved during the work underlying this thesis.The PTV can be used as a large volume injector, in so-called solvent vent mode. This technique was evaluated for the determination of PBDEs and as an interface for coupling dynamic sonication-assisted solvent extraction online to GC. The results show that careful optimization of the injection parameters is required, but also that the PTV is robust and yields reproducible results.PBDEs are commonly detected using mass spectrometry in electron capture negative ionization (ECNI) mode, monitoring bromine ions (m/z 79 and 81). The mass spectrometric properties of the fully brominated diphenyl ether, BDE-209, have been investigated. A high molecular weight fragment at m/z 486/488 enables the use of 13C-labeled BDE-209 as an internal surrogate standard.

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Tollbäck, Petter. "Large volume injection and hyphenated techniques for gas chromatographic determination of PBDEs and carbazoles in air /." Stockholm : Department of Analytical Chemistry, Stockholm University, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-367.

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Scarfe, Graeme Bryan. "The in vivo metabolism of substituted anilines and acetanilides in rat using hyphenated NMR spectroscopic techniques." Thesis, Birkbeck (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325321.

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Amaral, Juliano Geraldo. "Estudos das variações sazonais e intrapopulacional dos metabólitos secundários majoritários das folhas de \'Eremanthus glomerulatus Less\' (Asteraceae)." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/60/60138/tde-02102008-163904/.

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O trabalho buscou investigar as variações sazonais de metabólitos secundários em Eremanthus glomerulatus Less (Asteraceae). Embora não ser utilizada para fins medicinais esta espécie contem substâncias biologicamente ativas. Para este estudo, foram selecionados dez indivíduos de uma mesma população localizada na região do município de Ibiraci - MG, que durante um período de aproximadamente dois anos (06/2000 a 04/2002) tiveram um de seus ramos coletados mensalmente. Visando a análise das folhas destes ramos uma metodologia para extração e análise de seus metabólitos secundários majoritários por CLAE-UV foi desenvolvida e utilizada para determinação de suas variações sazonais. A identificação destes metabólitos se deu principalmente pelas técnicas hifenadas CLAE-DAD-EM e CLAE-DAD-EM/EM. Os metabólitos que não puderam ser identificados por estas ferramentas foram isolados do extrato etanólico foliar desta espécie e identificados por RMN de 1H e 13C e EM. Durante este estudo foi verificado que o envelhecimento das folhas resulta em uma significativa redução no conteúdo de todos os seus metabólitos secundários. Também foi possível identificar nove metabólitos secundários pertencentes as classes dos ácidos cafeoilquínicos, derivados fenólicos e flavonóides, dos quais foram isolados três, sendo dois ainda não relatados na literatura. Quanto a variação sazonal pode-se verificar que os indivíduos apresentam perfis metabólicos bem semelhante com diferenças quantitativas mas praticamente não apresentando variações qualitativas entre os indivíduos. Pode-se observar também que há um metabolismo bem diversificado no qual nem sempre todos os indivíduos apresentam aumento de produção de um mesmo metabólito em determinada estação do ano. Apesar das variáveis é possível definir o outono e a primavera como as estações que durante o estudo apresentaram os melhores índices de produção de praticamente todos os metabólitos analisados. Por fim pode-se concluir que as variações sazonais em E. glomerutalus são significativas e que são determinantes para definir a época de futuras coletas para posteriores estudos químicos ou farmacológicos. This study was performed to investigate the seasonal intrapopulational variations of the secondary metabolites in Eremanthus glomerulatus Less (Asteraceae). Although this species is not used for medicinal purposes, it contains biologically active substances. For this study, ten individuals from the same population located in the region of Ibirici city, Minas Gerais state, had one of their lbranches collected monthly for about two years (from 06/2000 to 04/2002). Aiming the analysis of the leaves from the branches, a methodology on UV-HPLC was developed and used for the extraction and analysis of major secondary metabolites to determine the seasonal variations. The identification of the metabolites has occurred mainly by the HPLC-DAD-MS and HPLC-DAD-MS/MS hyphenated techniques. The metabolites that could not be identified by these methods were isolated from ethanolic extract of leaves of these species and identified by NMR 1H and 13C and MS. During this study it was noticed that the aging of the leaves results in a significant reduction on the rate of all the secondary metabolites. It was also possible to identify nine secondary metabolites belonging to caffeoylquinic acids, phenolical derivatives and flavonoids, from which, three compounds were isolated, however two compounds wasnt described in the literature. Relating to the seasonal variation, it was possible to verify that the individuals present similar metabolic profiles with quantitative differences but practically without qualitative difference. It was also possible to observe that there is a diversified metabolism in which not all individuals present an increase in the production of the same metabolite on a specific season. Despite these variations, it is possible to define autumn and spring as the seasons that presented the best rates of production on practically all the analyzed metabolites. Finally, it is possible to conclude that the seasonal variation of E. glomerutalus is significant and decisive to define the right time for future collection for further chemical and pharmacological studies.

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Crotty, Sarah Charlotte [Verfasser], Ulrich Sigmar [Gutachter] Schubert, and Georg [Gutachter] Pohnert. "Characterization of macromolecular systems by mass spectrometry and hyphenated techniques / Sarah Charlotte Crotty ; Gutachter: Ulrich Sigmar Schubert, Georg Pohnert." Jena : Friedrich-Schiller-Universität Jena, 2017. http://d-nb.info/1177601435/34.

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Lu, Weiying. "Development of Radial Basis Function Cascade Correlation Networks and Applications of Chemometric Techniques for Hyphenated Chromatography-Mass Spectrometry Analysis." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1317231072.

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Morillo, Martín Diego. "Superparamagnetic iron oxide nanoparticles as arsenic adsorbent. Development of Nanofiber SPION Supports and Arsenic Speciation Using Synchrotron and Hyphenated Techniques." Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/129335.

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Los estudios que se han realizado en la presente tesis doctoral se basan en el desarrollo de una metodología de síntesis y caracterización de sistemas nanoestructurados como recurso innovador para la recuperación de arsénico en efluentes contaminados y la depuración de dichos efluentes. Estos materiales tienen como elemento común, el uso de las Superparamagnetic Iron Oxide Nanoparticles (SPION), con las que se han realizado diferentes estudios de adsorción para evaluar los parámetros de adsorción óptimos (tiempo de contacto, efecto del pH y de la concentración). Dichos estudios han permitido determinar la máxima capacidad de adsorción del SPION a la hora de extraer el elemento contaminante y observar como se ve afectada dicha capacidad de adsorción, en función de la especie existente del elemento contaminante. La elección de SPION se fundamenta en el empleo de la fuerte interacción Fe-As demostrada en muchos compuestos naturales, así como por su capacidad magnética. A partir de éste estudio, se han desarrollado diferentes sistemas adsorbentes en modo no soportados, basados en la funcionalización del SPION (NanoComposites) o bien empleando sistemas soportados, ya sean con esponja de celulosa (Forager® Sponge) impregnada de SPION o los más novedosos, sistemas basados en nanofibras (de acetato de celulosa y poliacrilonitrilo). En este último caso, dichos sistemas son sintetizados vía electrospinning y cargados con SPION con el objetivo de incrementar la superficie específica de adsorción y facilitar su posible aplicación en muestras reales. Todos los sistemas desarrollados disponen de un valor añadido, ya que las propiedades magnéticas del SPION permiten recuperar las nanopartículas que pueden quedar expuestas en las disoluciones contaminadas de una manera rápida y efectiva, evitando así, una contaminación con nanopartículas del efluente tratado. El trabajo realizado, ha permitido optimizar tanto la síntesis de SPION, vía co-precipitación, como el desarrollo y caracterización de los sistemas adsorbentes. Adicionalmente, tras determinar la máxima capacidad de adsorción para cada uno de los sistemas, se ha estudiado la selectividad de dichos sistemas por las especies de arsénico en presencia de iones metálicos (Cu2+, Ni2+ o Zn2+) y/o de los aniones más comunes en aguas (cloruro, nitrato, sulfato y fosfato). En lo referente a los estudios de especiación, se han aplicado técnicas de especiación directa (técnicas de radiación sincrotrón) e indirecta (acoplamiento HPLC-ICP-MS) para determinar la selectividad de los materiales frente a las diferentes especies inorgánicas de arsénico (arsenito o arsenato), obteniéndose resultados satisfactorios que denotan una elevada selectividad por As(V). Por otra parte, se han evaluado las características y propiedades de los diferentes sistemas adsorbentes. Dicha actividad ha comportado el empleo de diversas técnicas analíticas, desde la microscopia (SEM y TEM) que permiten conocer el tamaño, distribución y morfología de las nanopartículas y nanofibras, hasta técnicas que proporcionan información sobre las características estructurales y propiedades físico-químicas de los materiales. Así pues, los estudios llevados a cabo para la realización de esta tesis doctoral proporcionan un significativo avance en el desarrollo de una serie de potenciales sistemas adsorbentes, los cuales pueden ser aplicados para la eliminación de contaminantes altamente tóxicos como el arsénico en muestras reales. Dicha aplicación, se caracteriza por unos valores de eficiencia, eficacia y selectividad comparables, cuando no superiores a materiales existentes en el mercado. Un ejemplo de la transferencia tecnológica derivada de esta tesis doctoral, es la patente solicitada “Filtro de tratamiento de líquidos con nanopartículas de magnetita y procedimientos correspondientes”. Ref: P201330144 y con fecha de prioridad del 6 de Febrero de 2013. The studies that have been carried out in the present PhD thesis Project are based in the development of a synthesis methodology and characterization of nanostructured systems as an innovative facility for the recovery of arsenic from contaminated effluents and the purification of these effluents. These adsorbent materials have a base element, Superparamagnetic Iron Oxide Nanoparticles (SPION). With this nanoparticles have carried out arsenic adsorption experiments to evaluate the optimum adsorption parameters (contact time, pH effect and concentration effect). These studies have made it possible to determine the maximum adsorption capacity of SPION when the contaminant element is extracted, observe how is affected this adsorption capacity depending of the contaminant element existing specie. It is expected to use the high affinity and string interaction between Fe-As as it is proved in several natural compounds. Then, taking into account the previous work with SPION, different adsorbent systems have been developed, non-supported nanostructured systems by SPION surface functionalization (NanoComposites) or supported nanostructured systems as SPION loaded over a cellulose sponge (Forager® Sponge) and the most innovative, SPION loaded electrospun nanofibrous systems (with polymers such as cellulose acetate and polyacrylonitrile). In this last case, these systems have been synthesized by electrospinning techniques with the main aim of increase the specific surface area and to make easier the real sample applications. These nanostructured systems have an added value because of the SPION magnetic properties let recover the nanoparticles that are exposed in the contaminates solutions in a quick and effective way, avoiding then, an unwanted contamination with nanoparticles of the treated effluent. The developed work have made possible the SPION Synthesis by co-precipitation method was optimized and the development and characterization of the nanostructured adsorbent systems were performed successfully. Thus, apart from the maximum adsorption capacity determination for each system, arsenic selectivity of this systems was performed in presence of metal ions (Cu2+, Ni2+ o Zn2+) and/or in presence of most common interfering anions in water (chloride, nitrate, sulphate and phosphate). Regarding the speciation studies, direct (Synchrotron radiation techniques) and indirect (Hyphenated HPLC-ICP-MS) speciation techniques were put in practice to determine the selectivity of each system for the different inorganic arsenic species, arsenite or arsenate, obtaining successfully results of the arsenate selectivity for all systems. Furthermore, the characteristics and the properties of the adsorbent systems have been evaluated. Several techniques have been used, from microscopic techniques (SEM y TEM) that let measure and understand the size, distribution and morphology of nanoparticles and nanofibers, to other techniques as X-ray diffraction (XRD) or magnetization measures (SQUID) that provide information about structural characteristics and physico-chemical properties. All in all, this work provides knowledge, demonstrated advances and different nanostructured adsorbent systems that can be potentially applied to remove highly toxic contaminants such as arsenic. An example of the appropriate technologic transference derived from the PhD. Thesis is the Spanish Patent “Filtro de tratamiento de líquidos con nanopartículas de magnetita y procedimientos correspondientes”. Ref: P201330144 with priority date on Febrery 6th, 2013.

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Arroyo-Mora, Luis E. "The Use of Hyphenated Spectrometric Techniques for the Environmental Forensic Assessment of Non-Traditional Pollutants and Degradates in the Greater Florida Everglades." FIU Digital Commons, 2009. http://digitalcommons.fiu.edu/etd/144.

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A comprehensive investigation of sensitive ecosystems in South Florida with the main goal of determining the identity, spatial distribution, and sources of both organic biocides and trace elements in different environmental compartments is reported. This study presents the development and validation of a fractionation and isolation method of twelve polar acidic herbicides commonly applied in the vicinity of the study areas, including e.g. 2,4-D, MCPA, dichlorprop, mecroprop, picloram in surface water. Solid phase extraction (SPE) was used to isolate the analytes from abiotic matrices containing large amounts of dissolved organic material. Atmospheric-pressure ionization (API) with electrospray ionization in negative mode (ESP-) in a Quadrupole Ion Trap mass spectrometer was used to perform the characterization of the herbicides of interest. The application of Laser Ablation-ICP-MS methodology in the analysis of soils and sediments is reported in this study. The analytical performance of the method was evaluated on certified standards and real soil and sediment samples. Residential soils were analyzed to evaluate feasibility of using the powerful technique as a routine and rapid method to monitor potential contaminated sites. Forty eight sediments were also collected from semi pristine areas in South Florida to conduct screening of baseline levels of bioavailable elements in support of risk evaluation. The LA-ICP-MS data were used to perform a statistical evaluation of the elemental composition as a tool for environmental forensics. A LA-ICP-MS protocol was also developed and optimized for the elemental analysis of a wide range of elements in polymeric filters containing atmospheric dust. A quantitative strategy based on internal and external standards allowed for a rapid determination of airborne trace elements in filters containing both contemporary African dust and local dust emissions. These distributions were used to qualitative and quantitative assess differences of composition and to establish provenance and fluxes to protected regional ecosystems such as coral reefs and national parks.

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LA, MAIDA NUNZIA. "Development and validation of analytical methods with hyphenated chromatographic techniques for the determination of NPS and drugs of abuse in biological matrices." Doctoral thesis, Università Politecnica delle Marche, 2022. https://hdl.handle.net/11566/299808.

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Sin dal 1990 l'apparizione sul mercato di nuove sostanze psicoattive (NPS) è un fenomeno mondiale sempre crescente. Ogni anno vengono introdotte nuove sostanze nel mercato della droga come alternative legali alle sostanze controllate dalla legge. L’identificazione di queste nuove sostanze in matrici biologiche rappresenta una continua sfida per i laboratori di analisi. È estremamente importante sviluppare metodologie analitiche in grado di identificare sostanze sconosciute consentendone il monitoraggio e fornendo informazioni scientifiche riguardo la farmacocinetica, possibili range di tossicità ed effetti farmacologici. Oggi, le tecniche cromatografiche ifenate (tecniche basate sull’accoppiamento di più strumentazioni) sono dei mezzi molto utilizzati nella tossicologia clinica e forense. Il seguente progetto di ricerca ha lo scopo di sviluppare e validare nuovi metodi analitici basati su tecniche cromatografiche accoppiate alla spettrometria di massa e spettrometria di massa tandem per la determinazione delle NPS e delle classiche droghe d’abuso in matrici biologiche. In particolare, considerando la poliassunzione di droghe, è stato sviluppato un metodo di screening utilizzando la cromatografia liquida ad alta prestazione abbinata alla spettrometria di massa tandem (HPLC-MS-MS) per la determinazione di 77 NPS (appartenenti a diverse classi di sostanze), 24 droghe classiche e 18 metaboliti nel sangue, in urina e saliva. Attualmente, i cannabinoidi sintetici sono il più grande gruppo di NPS monitorato dall’Agenzia Europea per le Droghe (EMCDDA ). Due nuovi metodi analitici sono stati sviluppati per la determinazione dei cannabinoidi sintetici JWH-122, JWH-210 e UR-144 in saliva: un metodo in gascromatografia accoppiata alla spettrometria di massa (GC-MS) e un metodo complementare che utilizza la cromatografia liquida ad alta prestazione abbinata alla spettrometria di massa ad alta risoluzione (UHPLC-HRMS) per la quantificazione sia dei parent drugs che dei loro metaboliti. Infine, in risposta alla crescente diffusione di nuovi catinoni sintetici, viene presentato un metodo mirato per la loro identificazione e quantificazione mediante cromatografia liquida ad alte prestazioni e spettrometria di massa ad alta risoluzione (UHPLC-HRMS). Tutti i metodi qui descritti sono stati validati con successo e applicati a campioni reali (sangue, urina, saliva, capelli) fornendo risultati affidabili e dimostrando di essere metodologie sensibili utilizzabili in laboratori clinici e forensi. The emergence of new psychoactive substances (NPS) has been a growing global phenomenon since 1990. Every year new substances appear into the drug market as legal alternatives to illicit drugs. In this regard, the identification in biological matrices of emerging synthetic compounds represents a continuous challenge for analytical toxicologists. It is extremely important to develop suitable drugs analysis methodologies which can provide information on pharmacokinetics, pharmacodynamics effects and possible toxic concentration ranges, and on the diffusion of these unknown substances. Hyphenated chromatographic techniques have become powerful tools largely used in clinical and forensic toxicology. This research project aimed to develop and validate new analytical methodologies based on hyphenated chromatographic techniques for the determination of NPS and classical drugs of abuse in biological matrices. Considering the polydrug consumption, a comprehensive high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS-MS) screening method was developed for the determination of 77 NPS (belonging to different chemical classes), 24 classic drugs and 18 related metabolites in blood, urine, and oral fluid. Currently, synthetic cannabinoids are the largest group of NPS monitored by the European Monitoring Centre for Drugs and Drug Addiction and to investigate the oral fluid pharmacokinetics of JWH-122, JWH-210 and UR-144 two new methodologies were developed. A gas chromatography-mass spectrometry (GC-MS) method for the determination of parent compounds and a complementary ultra-high performance liquid chromatography high resolution mass spectrometry (UHPLC-HRMS) confirmatory method for the quantification also of their metabolites. Finally, to keep in pace with the increasing spread of new synthetic cathinones an ultra-high performance liquid chromatography high resolution mass spectrometry (UHPLC-HRMS) method is presented for their simultaneous targeted screening and quantification in hair samples of consumers. All methods described here have been successfully validated and applied to authentic samples (blood, urine, oral fluid, hair) providing reliable results and proving to be sensitive methodologies suitable for use in clinical and forensic laboratories.

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Zaffino, C. "EXPLOITING THE POTENTIALITY OF SURFACE-ENHANCED RAMAN SCATTERING (SERS) FOR THE IDENTIFICATION OF NATURAL DYES IN ANCIENT TEXTILES: FROM HYPHENATED TECHNIQUES TO IN-SITU ANALYSIS." Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/332247.

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Surface-enhanced Raman scattering (SERS) is nowadays a well-assessed spectroscopic tool for the identification of historical natural dyes in the scientific community of analytical chemists, even if not yet entirely established in the common practice of laboratories devoted to the chemical characterization of works of art. This technique is based on the enhancement of Raman bands that takes place when a molecule is placed in the proximity of, or possibly adsorbed on, a roughened metal surface, provided by a pre-treated electrode, a metal colloid or a metal thin film. Silver is the most frequently used metal, thanks to the relevant enhancement it provides with visible excitation wavelengths, and colloids are the preferred substrates for analytical applications, given their easiness of preparation. Researchers first composed databases of SERS spectra of natural dyes in solution obtained with different excitation wavelengths to provide suitable references for the identification of the same in ancient textiles and paintings. Subsequently, new protocols of analysis have been developed to improve the identification of dyes in complex matrices, such as micro-samples coming from valuable artistic and historical objects. In the present Ph.D. project, surface-enhanced Raman scattering is studied in order to overcome some limitations both inherent to the technique and to ancient colored samples and artifacts. The methodologies developed evolved from the knowledge of a very recent literature, with continuous cutting-edge progresses. In more detail, as suggested above, to complete the transfer of the SERS technique from the research laboratory to the specialized analytical laboratory, a further enlargement of the database is still required. Indeed, the range of natural dyes used historically worldwide in craftsmanship and art is really huge and, even if some of them were employed in different geographical areas, many others were typical of a given zone being obtained from local vegetable (or, less frequently, animal) sources. In order to contribute to accomplish this aim, a SERS study of anthocyanins by means of SERS was carried out for the first time and reported in the present doctoral thesis. The work regarded both SERS analyses of anthocyanins as pure molecules and in mixture with other compounds in plants and textiles. Moreover, the hypothesis of an anthocyanin content of the so-called folium dye, whose main chromophores are still unknown, was assessed. It is worth remembering that, even if SERS shows, as usual for vibrational spectroscopy, a remarkable specificity in the identification of an analyte, its use can be partially hindered when the sample is more properly a mixture of compounds, as frequently happens for natural dyes that contain many colored and uncolored substances and that were often used in mixtures to yield a given tint. Indeed, this is the reason why a separative technique, namely high-performance liquid chromatography (HPLC), is still the most widely employed analytical tool for this sort of studies, usually coupled with UV-visible diode-array detection (HPLC-PDA). In spite of its sensitivity, however, this kind of detection can sometimes lack in specificity. Therefore, SERS proposes itself as an alternative, or parallel, detection method for HPLC analysis of natural dyes. Few studies have been reported in the literature about the development of equipments combining HPLC and SERS techniques, mainly applied to the analysis of drugs. A part of the present project was therefore devoted to the optimization of a laboratory-made HPLC-PDA-SERS hyphenated system to be used specifically for the identification of natural organic dyes. Of course, being conceived for solutions, the application of SERS as well as of HPLC to the analysis of colorants in ancient objects requires as first step the extraction of the dyes from a sample drawn from the object itself. Dyestuffs were indeed fixed on textiles or incorporated in painting as metal complexes. Extractions are of course time-consuming, as well as obviously destructive with regard to the sample. For this reason, non-extractive protocols based on SERS analysis performed directly on the sample itself have been recently suggested in the literature. “Extractionless” analyses can be performed on textile fragments as such, or on samples previously hydrolyzed by acid vapors. In this latter case, usually a hydrolysis pre-treatment of micro-samples is executed, in order to break the dye-mordant complexes without removing the dye from textiles, followed by direct SERS analysis onto the sample. A further aim of the present project was indeed to contribute to the development of an “extractionless” protocol to be applied to the widest range of dyes and to the least amount of sample, possibly reducing problems such as the interference of the textile substrate and the fluorescence background typical of ancient samples. The use of a less-energetic source of radiation, as in the Fourier-transform Raman spectroscopy (1064 nm), was therefore investigated to match these aims. Finally, it should be noted that even extractionless methods are not completely respectful of the integrity of the artefact being examined, requiring a sample even if as small as possible. Being this an issue of the outmost importance for conservators, it is evident that an entirely non-destructive application of SERS technique would be highly desirable. Some attempts in this regard were also carried out, both at Duke University (USA) in collaboration with the research group of Prof. Tuan Vo Dinh and at the Department of Chemistry of Università degli Studi di Milano. Different solid nanoplatforms were experimented and tested for the enhancement of Raman signals of dyes directly on textiles, exploiting solid-solid interactions between the dyes and the nanomaterials with the final aim to allow the identification of these molecules without need of displacing the artefacts to which they belong from their site of storage. Finally, it is worth underlining that, as SERS protocols need to be tested not only on reference dyes, but also on ancient samples to verify their performance in real analytical problems, the present project investigated also the applicability of the SERS techniques developed for recognizing dyes in ancient textile samples from artistic collections.

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SHAH, MONIKA. "CHARACTERIZATION OF BIOLOGICALLY IMPORTANT VOLATILE AND NON-VOLATILE MOLECULES VIA HETEROATOM DETERMINATION USING CHROMATOGRAPHY AND MASS SPECTROMETRY." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1148309632.

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Ferreira, Leandro de Santis. "Análise de variação populacional e caracterização dos metabólitos secundários presentes nas folhas de Lychnophora granmongolense (Duarte) Semir & Leitão Filho." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/60/60138/tde-29042010-121931/.

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Uma das principais características da família Asteraceae é sua capacidade de produzir uma grande diversidade de metabólitos secundários que podem possuir efeitos terapêuticos ou tóxicos. Para verificar a existência de variações inter e intrapopulacionais na sua composição metabólica secundária de Lychnophora granmongolense (Duarte) Semir & Leitão Filho e caracterização desses metabólitos foi desenvolvida uma metodologia analítica em CLAE DAD. Essa metodologia permitiu a identificação de três compostos, vicenina-2, quercetina e pinocembrina, através da coinjeção de padrões, ou seja, pela comparação do tempo de retenção com padrões previamente isolados associados com os dados do espectro no UV. Com a utilização da técnica de espectrometria de massas, CLAE-DAD-EM e CLAE-DAD-EM/EM, foram identificadas quatro lactonas sesquiterpênicas (LST), centraterina, 4,5-di-idrocentraterina, lychnofolido e 15-desoxigoyazensolido. No estudo de variação populacional, os resultados indicaram grandes variações quantitativas e qualitativas tanto inter quanto intrapopulacionais para os metabólitos de alta e média polaridade. A análise dos metabólitos mais apolares presentes nas folhas permitiu a identificação de 8 triterpenos e 8 triterpenos acetilados. Contudo, esses metabólitos apresentam somente pequena variação que não é significativa. Assim, esse estudo contribuiu para o aumento do conhecimento sobre o ritmo metabólico dessa espécie. One of the main characteristics of plants of the Asteraceae family is their capacity to produce a huge diversity of secondary metabolites having therapeutic and toxic effects. An analytical method was developed based on HPLCDAD which was used to verify the existence of variations in Lychnophora granmongolense (Duarte) Semir & Leitão Filho secondary metabolite levels among species within populations and between distinct populations and to characterize the major secondary metabolites. Through this method three compounds, namely vicenin-2, quercetin and pinocembrin were identified by co-injection of standards. This identification was based on the comparison of retention time with isolated standards and the UV spectrum. Four sesquiterpenes lactones centratherin, 4,5-dihydrocentratherin, lycnopholide and 15-deoxygoyazensolide were identified by mass spectrometry techniques coupled with HPLC (HPLC-DAD-MS e HPLC-DAD-MS/MS). In the populational variation study, the results show large qualitative and quantitative differences among species within populations and between populations for high and medium polarity secondary metabolites. Eight triterpenes and eight acetyl triterpenes were identified by apolar compound analysis. However, small, insignificant variation was observed for these particular metabolites. Thus, this study contributed to an increase in the knowledge of the metabolic rhythm of this specie.

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Schmid, Christina Maria [Verfasser], and C. [Akademischer Betreuer] Barner-Kowollik. "Efficient Switching of RAFT to Hydroxyl Capped Polymers as a Versatile Scaffold for Block Copolymer Synthesis : and their Characterization with Advanced Hyphenated Techniques / Christina Maria Schmid. Betreuer: C. Barner-Kowollik." Karlsruhe : KIT-Bibliothek, 2012. http://d-nb.info/102511437X/34.

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Qvarnström, Johanna. "On the reliability of methods for the speciation of mercury based on chromatographic separation coupled to atomic spectrometric detection." Doctoral thesis, Umeå universitet, Kemi, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-111.

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This thesis deals with the reliability of methods for the speciation of mercury in environmental and biological samples. Problems with speciation methods that couple chromatography to atomic spectrometric detection and how to overcome the problems are discussed. Analytical techniques primarily studied and evaluated are high performance liquid chromatography-cold vapour-atomic absorption spectrometry (HPLC-CV-AAS), HPLC-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS), capillary electrophoresis-ICP-MS (CE-ICP-MS) and gas chromatography-ICP-MS (GC-ICP-MS). Applying a multi-capillary approach increased the analyte amount injected into a CE-ICP-MS system and improved the overall sensitivity. A microconcentric nebulizer with a cyclone spray chamber was shown to improve the detection limits for mercury species 3-13 times in HPLC-ICP-MS and 11-19 times in CE-ICP-MS compared to a cross-flow nebulizer with a Scott spray chamber. To decrease the interference of water vapour in HPLC-CV-AAS a Nafion dryer tube was inserted between the CV-generation and the detector. Methyl mercury was however lost in the Nafion unless it was reduced to elemental mercury prior transport through the dryer tube. During sample pre-treatment, incomplete extraction, losses and transformation (alkylation, dealkylation, oxidation and reduction) of mercury species can lead to significant errors (underestimation and overestimation) in the determination of the concentrations. Methods to detect and determine the degree of transformation as well as correct for errors caused by transformation are presented in the thesis. The preferable method use species-specific enriched stable isotope standards in combination with MS detection and a matrix based calculation scheme. This approach is very powerful as both the concentrations of the species as well as the degrees of transformation can be determined within each individual sample.

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Neto, Leonardo Gobbo. "Emprego de técnicas hifenadas na identificação de metabólitos secundários de \'Lychnophora ericoides\' Mart. (Asteraceae) e determinação de suas variações populacionais e temporais." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/60/60138/tde-02102008-165058/.

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A análise pelas técnicas hifenadas CLAE-DAD-EM e CLAE-DAD-EM/EM de extratos foliares de Lychnophora ericoides Mart. levou à identificação de 34 metabólitos secundários diretamente a partir dos extratos vegetais. Destes, 19 foram relatados pela primeira vez na subtribo Lychnophorinae. Uma metodologia para extração e análise destes metabólitos por CLAE-DAD foi desenvolvida, validada e utilizada para determinação de suas variações populacionais e temporais. Perfis metabólicos bem semelhantes, com diferenças quantitativas, mas não qualitativas, foram observados entre os indivíduos de uma mesma população. Entre as cinco populações analisadas, foi observado um metabolismo secundário bem mais diversificado, caracterizado pela presença de lactonas sesquiterpênicas, nas plantas da população de Ibiraci-MG. As concentrações mais elevadas de ácidos cafeoilquínicos foram encontradas no período da seca no cerrado (inverno) e as menores quando a planta se encontrava florida. Os teores de flavonóides foram maiores durante o período de chuvas (verão) e os de C-glicosilflavonas e lactonas sesquiterpênicas se mantiveram estáveis. Variações circadianas significativas de flavonóides e ácidos cafeoilquínicos também foram observadas nas duas populações nas quais estes fatores foram estudados. Foi verificado que o envelhecimento das folhas resulta em uma pronunciada redução no conteúdo de todos os metabólitos secundários e concentrações menores dos metabólitos foram observadas nas folhas dos ramos floridos em relação aos ramos sem flores de um mesmo indivíduo. Finalmente, conclui-se que as variações temporais e populacionais observadas em L. ericoides podem ser determinantes para a intensidade da atividade antiinflamatória e/ou analgésica desta planta, utilizada popularmente para estes propósitos. The analyses of Lychnophora ericoides Mart. leaves extracts by HPLC-DAD-MS and HPLC-DAD-MS/MS resulted in the identification of 34 secondary metabolites directly from the plant extracts. Nineteen of these metabolites are being reported for the first time in the Lychnophorinae subtribe. A method for the extraction and analyses of these metabolites by CLAE-DAD was developed, validated and employed for the determination of their populational and temporal variations. Very similar metabolic profiles, exhibiting quantitative but not qualitative differences, were found among each population individuals. Among the five studied populations, a more diversified secondary metabolism, characterized by sesquiterpene lactones presence, was observed for the plants collected at Ibiraci-MG. The highest concentrations of caffeoylquinic acids were found in the cerrado dry season (winter), and the lowest when the plants were blooming. The flavoinoid contents were higher during the rainy season (summer), while C-glucosylflavones and sesquiterpene lactones levels remained stable. Significant circadian variations were also detected regarding flavonoids and caffeoylquinic acids in the two populations analyzed on this respect. It was also found a pronounced reduction in the contents of all the secondary metabolites as the leaves get old. Lower levels of all the metabolites were also found for the flowery branches when compared to the non flowery ones in the same individual. Finally, it can be concluded that the temporal and populational variations detected in L. ericoides leaves could highly influence the intensity of the anti-inflammatory and/or analgesic activities of this plant, used in popular medicines for these purposes.

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Flis, Paulna. "Développement de méthodes analytiques pour une spéciation à grande échelle des composés métalliques dans les plantes." Thesis, Pau, 2013. http://www.theses.fr/2013PAUU3023/document.

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De nombreux métaux tels que, par exemple le Zn, le Fe, le Cu ou le Ni jouent un rôle essentiel dans la croissance et le développement normal des plantes car ils sont impliqués dans différents processus physiologiques pouvant être cependant perturbés par une carence ou un excès en métaux. Par conséquent, afin de réguler l'absorption des métaux, leur translocation et leur accumulation, les plantes ont développé des mécanismes divers, comme la production de métabolites de faible poids moléculaire pouvant se lier aux métaux. La connaissance de ces complexes métalliques et des processus qu'ils subissent dans les plantes peut être utilisée dans des études environnementales, nutritionnelles et toxicologiques. Cependant, cette connaissance était très limitée à cause de l'absence de méthodologie appliquée avec succès pour étudier la spéciation des traces de métaux dans les végétaux. Par conséquent, le but de cette étude fut le développement d'une méthodologie d'analyse des espèces métalliques dans des échantillons de plantes. La nouvelle approche est basée sur l'utilisation conjointe du (i) couplage HPLC – ICP MS permettant la détection de nombreuses espèces, souvent peu concentrées, contenant des métaux avec (ii) une identification en parallèle par couplage HPLC – electrospray Orbitrap MS/MS. Elle a permis l'identification (i) d’environ 60 espèces métalliques, la plupart jamais observées précédemment dans différents fluides (xylème, endosperme liquide) de Pisum sativum (petit pois) et (ii) de plusieurs complexes mixtes fer - aluminium - citrate chez Plantago almogravensis. La méthodologie développée a également été appliquée à (iii) la spéciation du sélénium dans Brassica nigra permettant l'identification de plus de 30 composés de faible poids moléculaire contenant du sélénium Numerous metals, such as, e.g. Zn, Fe, Cu or Ni play an essential role in normal plant growth and development as they are involved in different physiological processes that may be, however, disrupted by metal deficiency or excess. Therefore, to regulate metal uptake, translocation and accumulation plants have developed diverse mechanisms including the production of low molecular mass metal binding metabolites. The knowledge of these forms of metals and the processes they undergo in plants can be used in environmental, nutrition and toxicological studies. However, this knowledge was very limited as there was a lack of methodology that could be successfully applied to investigate trace metal speciation in plants. Therefore, the aim of this study was the development of the methodology for the analysis of metal species in complex plant samples. The novel approach is based on the use of combination of (i) HPLC – ICP MS coupling allowing the detection of numerous, often low concentrated, metal-containing species with (ii) a parallel identification using HPLC – electrospray Orbitrap MS/MS coupling. The developed approach allowed the identification of (i) ca. 60 different, mainly previously unreported metal species in saps of Pisum Sativum (green pea) and (ii) several mixed iron – aluminum – citrate complexes in Plantago almogravensis. This developed methodology was also applied to (iii) investigate selenium speciation in Brassica nigra allowing the identification of more than 30 selenium-containing low molecular mass compounds

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Shih, Ying, and 石瑩. "Micro Liquid Chromatography: Hyphenated Technique of Microbore Column ＆ Electrochemical Detector." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/16451635572327284983.

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博士 靜宜大學 應用化學研究所 83 Biogenic amines, including catecholamines and indoleamines, affect a number of important functions in the peripheral and central nervous systems. Investigation on levels of biogenic amines and their metabolites in a variety of physiological and disease states plays an important role in neuroscience. It has become routine to measure biogenic amines in biological samples in many research laboratories. There are many interfering substances in biological samples. Removing these interfering substances prior to analysis is an important pretreatment process. In this study, microdialysis and ultrafiltration techniques were used to pretreat sample. The collected dialysates or ultrafiltrate samples can be directly injected onto liquid chromatographic systems. Liquid chromatography with electrochemical detection is the most popular method for determining biogenic amines. Nevertheless, some of these biogenic amines in body fluids are below the detection limit of conventional systems. The use of microbore column leads to an increase peak resolution and detection sensitivity. Dual- channel electrochemical detectors were investigated in the confirmation of these biogenic amines. In order to achieve optimal detection limit, the application of new electrochemical detectors were also investigated.

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Lu, Shih-Chang, and 呂錫璋. "Studies of the Impurities of Uranium Oxide by ICP-AES on line Hyphenated Technique." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/39818893949344927316.

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碩士 文化大學 應用化學系 85 Uranium Oxide was dissolved with nitric acid and phosphorous acid in theanion form of [ UO2(HPO4)2 ]-2 ,then the sample solution of 0.5% phosphorousacid was controlled by a four channel peristaltic pump and a six-way adjust-able injection valve, pass through a Bio-Rad 50*8 cation column. The cationimpurities were absorbed onto the resin while the matrix of anion [ UO2(HPO4)2 ]-2 was drained. When the whole volume of Uranium solution through the column, adjust theinjection valve to 2M nitric acid solution to elutriate the impurities thathad been absorbed into the cation exchange column. this eluent was then determined by ICP-AES for the impurities of the Uranium Oxide. The resultsshow that more than 98% of Uranium matrix was separated by this method.The recovery of impurities of iron, copper,nickel, aluminum, and chromiumwas between 98.2-103% , relative standard deviation ( RSD ) were 0.3-13%and detection limits were 2-57ug/g.

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XING, LIYAN. "ION EXCHANGE CHROMATOGRAPHY COUPLED TO INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY: A POWERFUL TECHNIQUE FOR STABILITY CONSTANT DETERMINATION, SPECIATION ANALYSIS AND KINETIC STUDIES." Thesis, 2010. http://hdl.handle.net/1974/6111.

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Facile procedures based on hyphenated ion-exchange chromatography (IEC) and inductively coupled plasma mass spectrometry (ICP-MS) were developed to determine conditional stability constants, speciate chromium species and investigate the reduction of Cr(VI). 1. Improvements were made to a method previously developed to determine the conditional stability constant, Kf’, and chelation number, n, using IEC-ICP-MS. This method allowed the accurate determination of the conditional stability constant of a simple system. However, the corresponding chelation number was significantly different to the expected value because the principal assumption, i.e. that the ligand was in excess, was not realized in the experimentation. Furthermore, it neglected complexes other than that formed with EDTA4-. By taking into account these factors, accurate Kf’ and n were obtained for Co-EDTA and Zn-EDTA systems. 2. A simple method was developed for chromium speciation analysis at sub-µg L-1 level in potable water by IEC-ICP-MS. Cr(VI) and Cr(III) were separated on IonPac® AG-7 guard column within 7.5 minutes using gradient elution with 0.1 M ammonium nitrate and 0.8 M nitric acid. H2 collision/reaction interface gas eliminated chlorine-based and carbon-based polyatomic interferences on Cr detection. Water samples were analyzed directly, without any pretreatment. The accuracy of the method was verified through accurate analysis of riverine water certified reference material. Limits of detection of 0.02 and 0.04 µg L-1 for Cr(VI) and Cr(III), respectively, were obtained. 3. This speciation analysis method was then used for kinetics studies of Cr(VI) reduction in acidified riverine water. Water was spiked with Cr(VI), with or without Cr(III), and evolution of each Cr species with time was monitored by speciation analysis, showing that the reduction of Cr(VI) was a pseudo first order reaction. By plotting the logarithm of the peak area ratio of the instant Cr(VI) concentration over that of the original spiking versus time, the reaction rate constant was obtained as the slope. The reduction rate increased with decreasing pH and increasing temperature. The activation energy of the reaction at pH 1.3 was calculated using an Arrhenius plot. This method offers the advantages of small sample consumption, minimal sample manipulation, and easy data interpretation. Thesis (Ph.D, Chemistry) -- Queen's University, 2010-09-30 08:05:27.342

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Gras, RL. "Spectroscopic detection and hyphenated techniques in microfluidic enabled gas chromatography." Thesis, 2018. https://eprints.utas.edu.au/30041/1/Gras_whole_thesis_ex_pub_mat.pdf.

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This thesis introduces newly innovated techniques and associated novel method developments in gas chromatography. There are two major emphases presented in this work: The first emphasis is in improving selectivity, sensitivity, and portability of analytical instrumentation with the use of molecular spectroscopy technique as a gas phase detector. Performance, benefit, and impact of using spectroscopic techniques with focus on ultraviolet (UV) detection were investigated first with a gas phase photometer and subsequently with a diode array detector. As a selectable multiwavelength UV based detector, the diode array detector was originally designed for liquid chromatography but successfully repurposed for gas chromatography. Contemporary diode array detector brings ultraviolet − visible spectroscopy onto the capillary gas chromatography timescale. The range of analytes compatible with this detector was substantially expanded to include active compounds enabled by effective passivation techniques and to semi-volatile compounds with boiling point equivalent to hexadecene (285 °C) with the augmentation of a purposely designed heated optical cell. The optical cell was powered by a highly compact isothermal semiconductor positive temperature coefficient heater offering substantial benefits for miniaturized and portable analytical devices in key aspects such as safety in overheating, energy efficiency, size, scalability, and in discovering new thermal management strategies. The userselectable multi-wavelength, over a range of 190–640 nm affords efficient and effective analysis of many volatile and semi-volatile organic compounds. The second emphasis focuses on benefits of combining selective detection with contemporary planar microfluidic devices. Hyphenation, multi-hyphenation, and multidimensional approaches enhance analytical capabilities without compromising performance nor incurring additional analytical time. These approaches have resulted in the development and implementation of innovative analytical methods to address challenging problems encountered in the community of practice. When correctly applied, selective detection can substantially ease the burden of separation traditionally imposed on the analytical column, especially in complex sample matrices. Selective and sensitive detection are enablers to high-speed gas chromatography which are also critical components in the development of portable and hand-held analytical devices. Therefore, research conducted in this field is essential to the capability of sustainable development for gas chromatographic techniques. The synergy in combining a selectable multi-wavelength UV based detector with other contemporary selective detectors and hyphenated techniques like atomic emission detector (AED), micromachined differential mobility spectrometer (μDMS), and the mass spectrometer (MS) operating in selected ion monitoring mode was illustrated in challenging industrial applications. In this work, critical development, use, and implementation of planar microfluidics in capillary gas chromatography were realized with multiple chromatographic system configurations. The successful use of these devices for mid-point and post column backflush, for hyphenated techniques, and multi-dimensional gas chromatography are highlighted.

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Mnatsakanyan, Mariam. "Natural antioxidants and high performance liquid chromatography (HPLC) hyphenated screening techniques." Thesis, 2010. http://handle.uws.edu.au:8081/1959.7/496789.

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Reactive intermediates in the oxidative processes are among the major sources of primary catalysts that initiate oxidation in vivo and in vitro; a process that is one of the major causes of food quality deterioration and generation of chronic diseases. Antioxidants, both natural and synthetic, have been widely used at legal limits in food, medical and personal care industries. However, recently, the use of synthetic antioxidants has been severely restricted because of the evidence that suggests they may be harmful to human health. As such, the importance of screening naturally occurring alternatives, which are presumably safe, effective as dietary supplements or as processing aids, is increasing. Natural products are well known for their molecular biodiversity and are of great interest as potential source for novel antioxidant molecules. Due to the chemical complexity of natural products, determining their antioxidant content can be a formidable task, but at the same time likely to be worthwhile task. This thesis investigates the hyphenation of one- and multi-dimensional chromatography towards to profiling antioxidant content in natural products.

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MICALIZZI, GIUSEPPE. "Comprehensive lipidomics profiling in complex real samples using hyphenated chromatography techniques coupled to mass spectrometry detection." Doctoral thesis, 2019. http://hdl.handle.net/11570/3147312.

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Lipidomics, a branch of metabolomics, is a science that is based on the study of all lipids present in a biological system know as lipidome [1]. The study of lipids has assumed between the scientists considerable importance and attention with the knowledge that they are involved in many vital biological processes in humans, animals, plants and microorganisms. The scientific communities confirm that lipids play a key role as energy storage in animal and plant tissues and they are responsible for maintaining the structural integrity of cells as major components of membranes [2]. The complete characterization of lipids in human blood allows understanding the impact of dietary and lifestyle in the human health. Their dysregulation contributes to numerous diseases, such cardiovascular disease [3], diabetes [4, 5], obesity [6], cystic fibrosis [7], male and female infertility [8-10], and Alzheimer’s disease [11]. Lipids or fats are also the ingredients of foodstuff derived from both animal and plants. Fats represent almost 40% of dietary calories in developed countries, and their composition is obviously vital for a good nutrition. Dietary fats are essential for normal growth, development, and maintenance of body, and serve a number of important functions. In addition, fats contribute greatly to the palatability, taste and structure of foods [2]. Lipid samples from biological matrices are complex mixtures that require the use of chromatographic techniques for accurate identification and quantification. High performance liquid chromatography (HPLC) is usually used to separate intact lipid molecules. Lipid compounds can also be identified by their conversion with specific chemical reagents. In this case, the fatty acid (FA) composition of lipid classes is determined by gas chromatography techniques (GC). Probably, 99% of the analyses of FAs in foods are executed by using GC approach, previous derivatization of lipid compounds to corresponding fatty acid methyl esters (FAMEs) [12]. Given the complexity of the lipid matrices and the great structural diversity of these molecules, currently no single procedure is capable to separate lipid specie and a combination of LC and GC techniques must be used for a full characterization of the lipidome. The present PhD. thesis is placed into the lipidomic context. Specifically, the main aim of this research is the development of modern analytical technique, and improvement of the established methods, for the characterization of complex lipid matrices.

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Grevenstuk, Tomás. "Phytochemical studies and biological activity of carnivorous plants from the Mediterranean region." Doctoral thesis, 2010. http://hdl.handle.net/10400.1/1684.

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Tese de doutoramento, Ciências Biotecnológicas (Biotecnologia Vegetal), Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2010 In this thesis several studies were conducted with four carnivorous plant species which occur on Portuguese territory: Pinguicula lusitanica, Pinguicula vulgaris, Drosera intermedia and Drosera rotundifolia. Most habitats of these plants are threatened and natural populations are scarce, therefore micropropagation protocols were developed to produce biomass for the subsequent studies. Efficient micropropagation protocols were developed for P. lusitanica and D. intermedia enabling large scale biomass production, while protocols for the other two species have still to be optimized (in Chapter 2). The in vitro established cultures represent active germplasm collections of Portuguese natural populations and contribute therefore for their conservation. In Chapter 3 extracts prepared from micropropagated plant material were analyzed using state of the art HPLC-ESI-MS and HPLC-SPE-NMR equipment which enabled the identification of the major secondary metabolites produced by P. lusitanica and D. intermedia, directly from essentially crude extracts. The metabolites identified in P. lusitanica belong to the iridoid glucosides and caffeoyl phenylethanoid glycosides and D. intermedia was shown to produce mainly flavonoid glucosides, ellagic acid derivatives and the naphthoquinone plumbagin. The evaluation of the biological activities of these extracts, compiled in Chapter 4, showed that the methanol extract of P. lusitanica has considerable antioxidant activity and that the n-hexane extract of D. intermedia has high antimicrobial potential. In Chapter 5 a method for the extraction of plumbagin from micropropagated D. intermedia plants was optimized and its potential as an alternative for bioprospection evaluated. It was shown that the commercial exploitation of plumbagin from D. intermedia cultures might be viable and that UAE with n-hexane followed by an SPE purification step is an efficient procedure for obtaining large quantities of high purity plumbagin. It is hoped that this study represents an enrichment of the knowledge on these plants and contributes to their conservation and valorisation.

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Norková, Renáta. "Studium komplexů tebukonazolu s ionty kovů." Master's thesis, 2012. http://www.nusl.cz/ntk/nusl-307076.

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Tebuconazole belongs to widely utilized plant fungicides, mostly in vineyards. Its traces are present in plant tissues, wine as well as in soil. The aim of the study was to determine stoichiometries and stabilities of metal (Cu, Zn, Cd, Ca and Ag) complexes with tebuconazole (1) by means of electrospray ionization mass spectrommetry (ESI-MS). It was found that the complexes of tebuconazole with copper ions are particularly stable ([Cu(1)]+ has appearance energy 224 kJ·mol-1 , corresponding with the dissociation of the water molecule from the tebuconazole molecule), while the stability of another tebuconazole complexes is lower, about 150 kJ·mol-1 . In real environmental samples, the detection of 1 itself is hampered by its spreading into various species. The method involved here is based upon a hyphenation of electrochemistry (amperometry) and electrospray-ionization mass spectrometry (ESI-MS). It uses the fact that Cu creates very stable complexes with 1. We demonstrate that at appropriate potentials (at higher than 500 mV) Cu cations can be generated in an electrochemical cell and subsequently form complexes with 1 present in the sample. The resulting complex [Cu(1)]+ is detected with ESI-MS. The intensity of detected complexes depends on the concentration of 1 and the oxidation level of the...

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Wang, Chen-Yu, and 王震宇. "I. Pharmacokinetic and Metabolic Studies of Retrojusticidin B in RatsII. Application of LC-SPE-NMR Hyphenated Techniquei. Analysis and Identification of Lignans in Phyllanthus myrtifolius and P. urinariaii. Pharmacokinetic and Metabolic Studies of TM-1." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/86382512161362486679.

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博士 國立臺灣大學 藥學研究所 93 I. Pharmacokinetic and Metabolic Studies of Retrojusticidin B in Rats The pharmacokinetics and metabolism of retrojusticidin B, an anti-HIV reverse transcriptase agent isolated from Phyllanthus myritifolius, were studied in rats. The phase II conjugated metabolites were characterized after solvolysis and enzymatic hydrolysis. The oral bioavailabilities of retrojusticidin B, suspended in Tween 80 and in corn oil, were found to be 22.1% and 33.1%, respectively. The elimination half-lives (T1/2) were 22.9 and 36.2 minutes, respectively. The T1/2, clearance, and the volume of distribution (Vz) of retrojusticidin B estimated from i.v. were 24.5 min, 2.6 ± 0.4 L/min, and 90.6 ± 6.4 L, respectively. 9,9''-Secoretrojusticidin B was proved to be phase I metabolite. II. Application of LC-SPE-NMR Hyphenated Technique i. Analysis and Identification of Lignans in Phyllanthus myrtifolius and P. urinaria Application of LC-SPE-NMR hyphenated technique in analyzing lignans of great structural similarity, present in Phyllanthus urinaria L. and P. myrtifolius Moon, was undertaken. An LC system, composed of a C8 column, eluted with THF-H2O/ MeCN and detected at 225 nm, with good resolution for 7 lignans isolated from P. urinaria was developed. An LC system, composed of a C18 column, eluted with H2O/ MeCN and detected at 280 nm, also had good resolution for 7 pure lignans from P. myrtifolius. Hyphenation of this system to SPE-NMR provided very clean 1H NMR spectra for 9 and 7 lignans present in a partially purified and lignan rich fraction of P. urinaria and P. myrtifolius, respectively. The result demonstrates that LC-SPE-NMR is a very efficient and powerful tool in thorough structural identification of natural products, at least for those known, using a minute amount of plant materials. ii. Pharmacokinetic and Metabolic Studies of TM-1 in Rats and Pigs. A study on the metabolism of TM-1 /tartaric acid IV bolus in rats showed that, within 4 hours, laurolitsine, norglaucine, glaucinone, and TM-1-1 were the major metabolites in the blood of rats, and TM-1-1-like metabolites were also detected. Analysis of the extract of urine and feces of rats, collected within 2 days after iv injection of TM-1/tartaric acid, showed that both TM-1 and its metabolites probably were eliminated through hepatic-bile duct. Pharmacokinetic study of TM-1/tartaric acid in rats IV bolus showed that its blood concentration decayed with time; and both norglaucine and TM-1-1 were the major metabolites. Tissue distribution study indicated that the highest concentration of TM-1 was observed in kidney, followed by liver and heart, and decreased with time. Pharmacokinetics of TM-1 in the domestic pig via ear vein injection, with doses of 1.28 g/ 65kg, 0.45 g/ 67 kg, and 0.14 g/ 65 kg was studied. The blood samples were picked up from jugular vein at 5, 15, 30, 60, 120, 240 and 360 (480) min sharp after injection. HPLC analysis indicated that the concentration of TM-1 in the first 5 min was much lower than that expected, and TM-1 was still detectable after 6 hours’ injection. The metabolites, however, were not detected in this study.

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