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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Molecular charecterization and ageing of the sandarac resin and its principal component communic acid / Caractérisation moléculaire et vieillissement de la résine sandaraque et son composant principal de l'acide communique

Kononenko, Inna 20 September 2017 (has links)
La composition chimique de la résine sandaraque et de son composant principal l’acide communique a été étudiée par chromatographie en phase gazeuse – spectrométrie de masse (GC-MS), MALDI-TOF (désorption-ionisation laser assistée par matrice - temps de vol), ESI (ionisation par électronébuliseur) - Orbitrap, FTIR/ATR (spectroscopie infrarouge à transformée de Fourier/réflectance totale atténuée), spectroscopie de RMN (résonance magnétique nucléaire) à l'état solide et liquide. Six composés avec des squelettes labdane et pimarane ont été identifiés dans la résine commerciale. Les spectres de masse obtenus ont été interprétés et le comportement en spectrométrie de masse de ces diterpénoïdes dans les conditions de l’impact électronique a été décrit. L'analyse quantitative par la méthode de l'étalon interne a révélé que les diterpénoïdes identifiés ne représentaient que 10 à 30% de l'échantillon analysé. La complexité de la fraction réticulée de la résine commerciale sandaraque est bien reflétée par les spectres de masse MALDI-TOF et ESI-Orbitrap. En conséquence, les spectres de masse de MALDI-TOF comprenaient trois clusters de pics dans la gamme m/z de 300-900, et ceux d’ESI-Orbitrap contenaient cinq clusters de pics dans la gamme m/z de 300-1100. Les pics dans les clusters correspondent aux dérivés oxygénés des diterpénoïdes. Les résultats obtenus à partir des expériences RMN par IRCP (Inversion Recovery Cross-Polarization) ont révélé le caractère rigide des échantillons de la résine sandaraque analysés et justifiaient l'hypothèse que le reste de l'échantillon, qui ne pouvait être quantifié par la méthode de l'étalon interne, aurait un caractère polymère. / The chemical composition of sandarac resin and its principal component communic acid was investigated by gas chromatography-mass spectrometry (GC-MS), MALDI-TOF (Matrix Assisted Laser Desorption Ionization - Time of Flight), ESI (Electrospray ionization)-Orbitrap, FTIR/ATR (Fourier transform infrared spectroscopy/Attenuated total reflectance), liquid- and solid state NMR (Nuclear magnetic resonance) spectroscopy. Six compounds with labdane and pimarane skeletons were identified in the commercial resin. The obtained mass spectra were interpreted and the mass spectrometric behaviour of these diterpenoids under EI conditions was described. Quantitative analysis by the method of internal standard revealed that identified diterpenoids represent only 10–30% of the analysed sample. The complexity of the reticulated fraction of the commercial sandarac resin was well reflected by the MALDI-TOF and ESI-Orbitrap mass spectra. As a result, MALDI-TOF mass spectra comprised three clusters of peaks in the m/z range of 300–900, and for the ESI-Orbitrap mass spectra contained five clusters of peaks in the m/z range of 300–1100. The peaks in the clusters corresponded to the oxygenated derivatives of the diterpenoids. The results obtained from the IRCP (Inversion Recovery Cross-Polarization) experiments revealed the rigid character of the sandarac resin samples analyzed and justified the hypothesis that the rest of the sample, which could not be quantified by the method of internal standard, would have a polymeric nature.
12

Applications of Mass Spectrometry for Qualitative Analysis and Imaging of Microcystins in Mouse Tissues, Cyanobacterial Cells and Water

Kucheriavaia, Daria January 2020 (has links)
No description available.
13

Non-Integer Root Transformations for Preprocessing Nano-Electrospray Ionization High Resolution Mass Spectra for the Classification of Cannabis

Tang, Yue, tang 01 October 2018 (has links)
No description available.
14

Contribution à l'étude du lien entre Annonaceae et parkinsonisme : identification et quantification d'acétogénines par déréplication; métabolisation de phase I et approche de la distribution de l'annonacine / Contribution to the study of the relationship between Annonaceae and parkinsonisms : identification and quantification of acetogenins by dereplication; phase I metabolism and approach of the distribution of annonacin.

Le Ven, Jessica 03 February 2012 (has links)
Dans les Antilles françaises, une proportion anormalement élevée de parkinsonismes atypiques sporadiques – des tauopathies – est observée. Un lien avec la consommation de plantes de la famille des Annonaceae, en particulier Annona muricata L. (corossol) a été démontré. Les acétogénines d’Annonaceae, des inhibiteurs puissants du complexe I de la chaine respiratoire mitochondriale, sont considérées comme des toxines candidates. L’annonacine, une acétogénine représentative, majoritaire dans A. muricata, est neurotoxique in vitro et in vivo. L’Agence Française de Sécurité Sanitaire des Aliments a exprimé ses doutes quant à ce problème de santé publique. Elle insiste sur l’importance d’évaluer l’exposition des consommateurs d’Annonaceae aux acétogénines, et de déterminer les paramètres pharmacocinétiques de ces molécules. Au cours de cette thèse, nous avons cherché à répondre à ces interrogations, avec l’annonacine pour modèle. Après l’analyse structurale d’acétogénines étalons, une méthode de déréplication puissante et innovante a été mise au point par CLHP-ESI-LTQ-Orbitrap® avec infusion post-colonne de lithium. Les profils complets des acétogénines d’extraits bruts issus d’un nectar d’A. muricata et d’un alcool d’Annona cherimolia Mill. (annone, chérimole) ont été élucidés, mettant en évidence une composition plus complexe et plus variée que celle envisagée dans la littérature. A. cherimolia n’avait pas été identifiée comme une source d’exposition jusqu’à maintenant. Des données quantitatives ont été obtenues par CLHP-DAD-MS, à partir d’une quinzaine d’échantillons de produits commerciaux, confirmant une exposition humaine importante à ces molécules par voie alimentaire, via des produits d’origines géographiques, de statuts et de modes d’obtention variés. Des travaux préliminaires d’étude du passage de l’annonacine à travers des membranes biologiques ont été amorcés (modèles de barrières intestinale – Caco-2 – et hémato-encéphalique – hCMEC/D3). Une étude de métabolisation de phase I de l’annonacine sur microsomes de foie de Rat a permis d'identifier 25 métabolites mono-hydroxylés par CLHP-ESI-LTQ-Orbitrap®. Seuls trois d’entre eux sont observés avec des microsomes humains. Ces métabolites ont été obtenus par hémisynthèse (bioconversion, catalyse par porphyrines) et leur structure a été déterminée. Les résultats montrent que cette étape de métabolisation n’est pas cruciale dans le devenir de l’annonacine, et ne peut expliquer de susceptibilité différentielle aux acétogénines. Après la présentation de rappels concernant les Annonaceae, les parkinsonismes et leurs formes atypiques guadeloupéennes et tropicales, puis d’aspects méthodologiques en spectrométrie de masse, nos travaux de phytochimie analytique, d’analyse métabolique, d’hémisynthèse et de détermination structurale sont présentés, et discutés en regard d’un problème de santé publique potentiellement large et préoccupant. / In the French West Indies, an unusually high proportion of atypical sporadic parkinsonisms - tauopathies - is observed. A link between these atypical parkinsonisms and the consumption of plants of the Annonacea family, Annona muricata L. (soursop) was demonstrated. The Annonaceous acetogenins are potent inhibitors of complex I of mitochondrial respiratory chain and are considered to be in vitro toxins candidate. The major acetogenin in Annona muricata, annonacin, is neurotoxic in in vitro and in vivo models. Afssa (Agence Française de Sécurité Sanitaire des Aliments) expressed its concern regarding this public health problem. The Agency reports the importance of assessing consumers ‘exposure to Annonaceous acetogenins, and of determining the pharmacokinetic of these molecules. In this thesis, we sintended to answer these questions, with annonacine as a model. After the structural analysis of acetogenins standards, a powerful and innovative method of dereplication was developed by HPLC-ESI-LTQ-Orbitrap ® with post-column infusion of lithium. Complete acetogenins profile in crude extracts from nectar of A. muricata and from an alcohol of Annona cherimolia Mill. (Annona, cherimoya) were elucidated, revealing a more complex and more varied composition than that proposed in the literature. A. cherimolia had not been identified as a source of exposure to date. Quantitative data were obtained by HPLC-DAD-MS, from fifteen samples of commercial products, confirming an important human exposure to these molecules through food products of varied geographical origins, status and methods. Preliminary works to study ability of annonacin to cross biological membranes have been initiated (intestinal barrier models - Caco-2 - and blood-brain barrier - hCMEC/D3). A study of phase I metabolism of annonacin in rat liver microsomes allowed the identification of 25 mono-hydroxylated metabolites by HPLC-ESI-LTQ-Orbitrap®. Only three of them were observed with human microsomes. These metabolites were obtained by semisynthesis (bioconversion, porphyrin mediated catalysis) and their structure was determined. The results show that phase metabolism is not critical in the becoming of annonacin, and cannot explain a differential susceptibility of acetogenins. After a presentation of the Annonaceae family, of parkinsonism – including atypical and guadeloupean forms then of and methodological aspects of mass spectrometry, analytical phytochemistry of our work, metabolic analysis, semisynthesis and structure determination are proposed, and discussed in the context of a public health problem and potentially broad concern.
15

Etude d'aérosol atmosphérique par spectrométrie de masse à très haute résolution / High resolution mass spectrometry for the study of atmospheric aerosol.

Salque-Moreton, Guillaume 11 March 2014 (has links)
L'aérosol atmosphérique a des effets sur le changement climatique global et un impact sanitaire non-négligeables. Dans l'aérosol atmosphérique terrestre, les composés organiques représentent une fraction importante. Du fait de l'extrême complexité de cette fraction organique et des processus dynamiques qui l'animent, une fraction non négligeable de celle-ci n'est pas clairement identifiée à ce jour malgré des techniques d'analyses toujours plus nombreuses. Dans cette thèse, nous avons voulu explorer la richesse d'information fournie par une technique innovante : la spectrométrie de masse à haute résolution (HRMS). La haute résolution du LTQ-Orbitrap fournit une extrême précision sur la masse des molécules analysées et permet d'en identifier les formules brutes. Tout d'abord, nous avons utilisé cette nouvelle méthode de caractérisation afin d'élucider en laboratoire des mécanismes de production de l'aérosol se déroulant en phase aqueuse. Associée à une caractérisation par RMN, la HRMS nous permet d'identifier des voies de fabrication de composés de faible poids moléculaires (acides carboxyliques, aldéhydes, cétone) ainsi que des composés à haut poids moléculaire : les oligomères formés se transforment en HULIS au cours de leur vieillissement. Le fait que la méthacroléine (MACR) et la méthyl-vinyl-cétone (MVK), les deux principaux produits d'oxydation de l'isoprène, forment des AOS en phase aqueuse avait été précédemment montré. Ce travail montre que les précurseurs des AOS sont différents selon l'isomère et que les séries d'oligomères formées atteignent 1400 Da.. L'étude HRMS des produits permet de proposer un mécanisme radicalaire d'oligomérisation de la MVK. L'analyse HRMS des produits de la MACR montre qu'en plus du mécanisme valable pour la MVK, la réactivité de la MACR engendre co-polymérisation et production d'Hulis. Une signature HRMS des Hulis a été mise en évidence. Ensuite, nous avons utilisé les méthodes de traitement de données HRMS pour tenter de les appliquer à l'identification d'aérosol ambiant. Les composés organiques représentent la fraction majeure des particules de l'aérosol atmosphérique ; une grande partie reste mal identifiée. Une compréhension détaillée des sources et des procédés de transformations est nécessaire. L'investigation de la composition chimique des particules de matière fine et ultrafine peut être apporter par HRMS. L'ESI-Orbitrap apporte une description moléculaire qui détermine les propriétés chimiques et physiques de l'aérosol organique. Les particules ont été échantillonnées selon leur taille respective. Les prélèvements ont été fait à Grenoble en été et en hiver. Une comparaison saisonnière permet d'identifier des signatures chimiques différentes. Enfin, une intercomparaison est établie avec des échantillons d'une troisième campagne prélevées en proximité routière: MOCOPO. / Atmospheric aerosol has an important impact on the radiative balance of Earth. Organics compounds represent the major fraction of atmospheric aerosol particles; a large part is still not well characterized. A detailed understanding of the sources, transformations processes and fates of organics aerosols is needed. This work investigates the ability of the ESI-Orbitrap to characterize organics molecules of aerosol. Firstly, experimental and analytical methods were developed to unveil mechanistic ambiguities that were previously shown. Methacrolein (MACR) and methyl vinyl ketone (MVK) (the two main gas phase atmospheric oxidation products of isoprene) were known to form oligomers and secondary organic aerosol (SOA) upon aqueous phase OHoxidation and subsequent water evaporation. For the two precursors, ESI-MS analysis of the reacting solutions brought clear evidence for the formation of oligomer systems having a mass range of up to 1400 Da.. Taking advantage of the regularities observed in the oligomer systems, the ESI-HRMS data were used to propose stoichiometries for more than 75% of the observed signal. Moreover, we show here that MACR oligomers aging give rise to HULIS production. In addition, global estimates of secondary organic aerosol (SOA) formation flux show that current descriptions miss a large fraction of the sources. This gaping underestimation has been linked to a poor understanding of aerosol functionalization in the atmosphere and lead to the formation of a new conceptual framework for the description of the aerosol, based on volatility versus polarity plots. This new framework is almost exclusively based on High Resolution Time of Flight Aerosol Mass Spectrometer(HR-Tof-AMS) data, as this instrument gives access to average H:C, N:C and O:C ratios for the bulk aerosol. The AMS estimates for O:C and H:C ratios are thus based on heavy fragmentation of organics followed by stoichiometry attribution on those fragments. Given the resolution of the HR-ToF-AMS, such an attribution is not feasible above a certain mass, making fragmentation a necessary aspect of the measurement. Conversely, Orbitrap-HRMS provide a resolution of 100,000 at m/z 400, with a mass range 50 – 2000 amu, enabling stoichiometry retrieval up to higher masses than the AMS. Coupled to a “soft” electrospray ionization method, Orbitrap-HRMS gives O:C and H:C ratios on entire molecules in the analysed mixture. We used samples from three contrasted field campaigns: the two first at an urban kerbside site in summer and in winter, the third one in the roadway vicinity (Grenoble, France). Accelerated Solvent Extraction provides a clear overview of the chemical composition of organic extracts from aerosol particles collected at different season at an urban site. The elemental composition was obtained within 2-5 ppm, on the range 150-300 m/z. However, this study shows that both ionization polarity were needed to get a complete picture of the chemical composition of the samples. We showed that Esi-Orbitrap-HRMS allows to compute a statistical distribution of the elementary ratios that is different from a simple average value. Keywords: HRMS, SOA.
16

Numerical Investigation of Segmented Electrode Designs for the Cylindrical Ion Trap and the Orbitrap Mass Analyzers

Sonalikar, Hrishikesh Shashikant January 2016 (has links) (PDF)
This thesis is a numerical study of fields within ion traps having segmented electrodes1. The focus is on two cylindrical ion trap structures, two Orbit rap structures and one planar structure which mimics the field of the Orbit rap. In all these geometries, the segments which comprise the electrodes are easily Machin able rings and plates. By applying suitable potential to the different segments, the fields within these geometries are made to mimic the fields in the respective ideal structures. This thesis is divided into 6 chapters. Chapter 1 presents introduction and background information relevant to this work. A brief description of the Quadrupole Ion Trap (QIT) and the Orbit rap is given. The role of numerical simulations in the design of an ion trap geometry is briefly outlined. The motivation of this thesis is presented. The chapter ends by describing the scope of the thesis. Chapter 2 presents a general description of computational methods used throughout this work. The Boundary Element Methods (BEM) is first described. Both 2D and 3D BEM are used in this work. The software for 3D BEM is newly developed and hence 3D BEM is described in more detail. A verification of 3D BEM is presented with a few examples. The Runge-Kutta method used to compute the trajectory of ion is presented. A brief overview of the Nelder-Mead method of function minimization is given. The computational techniques specifically used to obtain the results in Chapter 3, 4 and 5 are presented in the respective chapters. Chapter 3 presents segmented electrode geometries of the Cylindrical Ion Trap (CIT). In these geometries, the electrodes of the CIT are split into number of mini-electrodes and different voltages are applied to these segmented electrodes to achieve the desired field. Two geometries of the segmented electrode CIT will be investigated. In the first, we retain the flat end cap electrodes of the CIT but split the ring electrode into five mini-rings. In the second configuration, we split the ring electrode of the CIT into three mini-rings and 1The term ‘segmented electrode’ used in this thesis has the same connotation as the term ‘split-electrode’ used in Sonalikar and Mohanty (2013). also divide the end caps into two mini-discs. By applying different potentials to the mini-rings and mini-discs of these geometries we will show that the field within the trap can be optimized to desired values. Two different types of fields will be targeted. In the first, potentials are adjusted to obtain a linear electric field and, in the second, a controlled higher order even multipole field are obtained by adjusting the potential. It will be shown that the different potentials to the segmented electrodes can be derived from a single RF generator by connecting appropriate capacitor terminations to segmented electrodes. The field within the trap can be modified by changing the value of the external capacitors. Chapter 4 presents segmented electrode geometries which are possible alternatives for the Orbitrap. Two segmented-electrode structures, ORB1 and ORB2, to mimic the electric field of the Orbitrap, will be investigated. In the ORB1, the inner spindle-like electrode and the outer barrel-like electrode of the Orbitrap are replaced by rings and discs of fixed radii, respectively. In this structure two segmented end cap electrodes are added. In this geometry, different potentials are applied to the different electrodes keeping top-bottom symmetry intact. In the second geometry, ORB2, the inner and outer electrodes of the Orbitrap are replaced by an approximate step structure which follows the profile of the Orbitrap electrodes. For the purpose of comparing the performance of ORB1 and ORB2 with that of the Orbitrap, the following studies will be undertaken: (1) variation of electric potential, (2) computation of ion trajectories, (3) measurement of image currents. These studies will be carried out using both 2D and 3D Boundary Element Method (BEM), the 3D BEM is developed specifically for this study. It will be seen in these investigations that ORB1 and ORB2 have performance similar to that of the Orbitrap, with the performance of the ORB1 being seen to be marginally superior to that of the ORB2. It will be shown that with proper optimization, geometries containing far fewer electrodes can be used as mass analysers. A novel technique of optimization of the electric field is proposed with the objective of minimizing the dependence of axial frequency of ion motion on the initial position of an ion. The results on the optimization of 9 and 15 segmented-electrode trap having the same design as ORB1 show that it can provide accurate mass analysis. Chapter 5 presents a segmented electrode planar geometry named as PORB used to mimic the electric field of the Orbit rap. This geometry has two planes, each plane consisting of 30 concentric ring electrodes. Although the geometry of PORB does not have conventional inner and outer electrodes of the Orbit rap, it will be shown that by selecting appropriate geometry parameters and suitable potentials for the ring electrodes, this geometry can trap the ions into an orbital motion similar to that in the Orbit rap. The performance of the planar geometry is studied by comparing the variation of potential, ion trajectories and image current in this geometry with that in the Orbit rap. The optimization of applied potentials is performed to correct the errors in the electric field so that the variation of axial frequency of ions with their initial position is minimized. Chapter 6 presents the summary and a few concluding remarks
17

Determinação do perfil de compostos fenólicos na própolis vermelha de Alagoas usando técnicas de fingerprinting (impressão digital) com LC-Orbitrap-FTMS e o software MZmine. / Determination of the profile of phenolic compounds in red propolis of Alagoas using fingerprinting techniques with LC-Orbitrap-FTMS and MZmine software

Souza, Naiana Soares de 15 August 2014 (has links)
Red Propolis northeastern Brazil (Alagoas, Brazil) has been widely studied for their biological activity against parasites, microorganisms. The composition of propolis varies according to geographic region and seasonality. Currently only isoflavanas, isoflavones and some propolones / guttiferones identified in propolis in Alagoas. The aim of this study was to apply modern methods of analysis of fingerprinting and screening (Screening), using LC-Orbitrap-FTMS in combination with MZmine software for extracting data from molecular ions to carry out such studies of propolis. Four propolis samples collected in two different towns of state of Alagoas and two of Pernambuco -. Brazil in the month of June / July 2012 The 2 samples of red propolis originating Alagoas (5.0 g) were subjected to extraction with ethanol to obtain their crude extracts, the remaining sample were already sold in the form of crude extract. The extracts solubilized in ethanol, diluted to a concentration of 1mg/mL, and injected directly into the LC-Orbitrap-FTMS, MS data extracted using the software MZmine 02.10. The precise masses of the components of the extracts compared with a database of online data. The LC-FTMS analysis combined with extraction and search database online with MZmine showed the presence of over 2,000 ion in the extract but only 210 could be a probable identification. In the Histogram, analysis showed phenolic groups/chalcones acids; isoflavones/isoflavans/ pterocarpans; propolones/guttiferones/bflavonoids specific mass of bands of common substances such as propolis, present as major compounds. Samples showed differences in the chemical profile, but all showed a high frequency of propolonas, isoflavones, terpenes and guttiferones / terpenosideos. Software MZmine and techniques of LC-FTMS and are extremely applicable for the testing fingerprint and identification of new phenolic compounds, not idetificavéis by conventional techniques phytochemical present in complex matrices. / Fundação de Amparo a Pesquisa do Estado de Alagoas / A Própolis vermelha do nordeste brasileiro (Alagoas, Brasil) tem sido amplamente pesquisada por sua atividade biológica contra diversos tipos de microrganismos. A composição da própolis varia de acordo com a região geográfica e a sazonalidade. Atualmente isoflavonoides e algumas propolonas/guttiferonas foram identificados na própolis vermelha de Alagoas. O objetivo deste estudo foi aplicar métodos modernos de análise de Impressão digital e triagem (Screening), usando LC-Orbitrap-FTMS em combinação com o software MZmine para a extração de dados dos íons. Quatro amostras de própolis foram coletadas: duas na cidade Marechal Deodoro no estado de Alagoas e duas na cidade de Igarassu no estado de Pernambuco – Brasil durante o mês de Junho/Julho de 2012. As amostras de Própolis vermelha de Alagoas, cinco gramas de cada amostra, foram submetidas a extração com etanol para obtenção de seus extratos brutos, as demais foram cedidas sob a forma de extrato bruto. Os extratos foram solubilizados em etanol e diluídos para a concentração de 1mg/mL e injetados diretamente no LC-Orbitrap-FTMS. Os dados de MS foram extraídos usando o software MZmine 2.10. As Massas exatas dos componentes dos extratos foram comparadas com um banco de dados on-line. A análise de LC-FTMS combinada com extração e pesquisa em banco de dados on-line com MZmine demonstrou presença de mais de 2.000 íons no extrato, onde 210 puderam ter uma identificação provável. A análise do Histograma de frequência íons mostrou agrupamentos de ácidos fenólicos/chalconas; isoflavonoides/ isoflavanas/pterocarpanos; propolonas/guttiferonas/ biflavonoides em faixas de massas específicas como substâncias comuns a própolis vermelha e presentes como substâncias majoritárias. Apesar das amostras apresentarem diferenças no perfil químico, todas continham alta frequência dos agrupamentos vistos no histograma. O software MZmine e as técnicas de LC-FTMS são extremamente aplicavéis para identificação de novos compostos fenólicos, não idetificavéis por técnicas convencionais de fitoquímica presentes em matrizes complexas.
18

Analýza antimikrobiálních peptidů v jedových žlázách čmeláků / Analysis of antimicrobial peptides in venom glands of bumblebees.

Janechová, Daniela January 2012 (has links)
The growing resistance of bacteria to traditional antibiotics promotes the interest in finding new substances for their production. Antimicrobial peptides have comparable effect to conventional antibiotics, but a different mechanism of action and they do not provoke bacterial resistance. These peptides were characterized in all forms of multicellular organisms. Hymenoptera venom contains many biologically active substances including antimicrobial peptides. For this reason, this thesis focuses on the acquisition of antimicrobial peptide sequences from selected species of bumblebees (Bombus terrestris, B. hortorum, B. hypnorum, B. pratorum, B. lucorum, B. lapidarius, B. humilis and B. bohemicus). The isolation from the venom glands was performed by high performance liquid chromatography with reversed phases. Subsequent analysis was performed using the methods of mass spectrometry, matrix-assisted laser desorption/ionization with time of flight analyzer and electrospray ionization connected with hybrid linear ion trap analyzer with orbitrap. The sequences for the found peptides were determined by tandem mass spectrometry methods "de novo" and Edman degradation. In this work we characterized 17 sequences of peptides extracted from bumblebee venom glands for which antimicrobial activity was determined...
19

Non-target screening of sediment samples fromthe Canadian Arctic: comparing two different gas chromatography – high resolution mass spectrometry (GC-HRMS) techniques

Timner, Mathilda January 2022 (has links)
Since the late 18th century, chemicals have been industrially produced, and used by consumers. Today, the number of registered chemicals are over 150 000 in North America and Europe alone, and the number is predicted to increase. Industrial or anthropogenic chemicals can, directly or indirectly, be released into the ecosystem during their lifetime, where they can cause harm to human health and the environment. Depending on their properties, chemicals can travel far away from its source, causing global contamination. Through this, the Arctic region becomes a sink for many different types of contaminants. Because of the danger certain chemicals pose, techniques to detect and identify them in environmental samples have evolved during recent years. In these cases, non-targeted screening methods are commonly used to characterise contaminants in samples.In this study, surface sediment samples were collected on three locations in the Hudson Bay (Canada). The samples were analysed using two different instruments: a comprehensive two-dimensional gas chromatograph coupled to a high resolution time-of-flight mass spectrometer (GC×GC-HR-ToF-MS) and a gas chromatograph coupled with a Orbitrap mass spectrometer (GC-Orbitrap-MS). After data acquisition and processing, certain components were identified in both datasets, and their semi-quantitative concentrations were calculated.Overall, 32 compounds were detected and identified in the Orbitrap dataset, and 17 of these were also detected in the GC×GC dataset. The concentration was determined semi-quantitively for the identified compounds and ranged from 0.005–333 ng/g dry weight (d.w.) for the Orbitrap dataset, and 0.013–278 ng/g d.w. for the GC×GC dataset, which was below, or in the lower half, of concentration ranges from previous studies. Overall, the data processing for Orbitrap data seems to be more advanced and evolved than for GC×GC data, causing differences between the results from the two instruments.
20

Trace amount analysis of common explosives in bodies of water using UHPLC-HRMS Orbitrap

Olsson, Felix January 2024 (has links)
Topical inquiries for the Swedish Defence Research Agency (FOI) include analysis of explosive substances in different sample types. Research into explosives in complex matrixes can provide an analytical support function for forensic investigation i.e. tools for areas such as finding bomb factories, identification and risk analysis of home-made explosives (HME) and improvised explosive devices (IED) as well as preventive measures against maliciously intended use of explosives. Additionally, the research may lay the groundwork for indications of health- and environmental hazards. Utilizing state-of-the-art equipment and years of extensive expertise, FOI is able to carry out these types of research tasks to provide security and sustainability for society. The aim of this thesis project is to establish and validate developed methods for collecting, extracting, separating, and detecting trace amounts of explosives in various bodies of water using a solid-phase extraction (SPE) robot and a high-resolution (HR) mass spectrometer (MS) connected to an ultra-high-performance liquid chromatograph (UHPLC). Particular areas of interest include locations in the Stockholm archipelago where experimental detonations of explosives have taken place. Overall, UHPLC-HRMS analysis provides a powerful tool for analyzing explosives in complex matrixes with unambiguous and reliable measurement data. The compounds of investigation were hexogen (RDX), octogen (HMX), pentyl (PETN), and trotyl (TNT). To summarize, during the course of the thesis, trace amounts of some explosives were detected and quantified in various bodies of water. Furthermore, the applied method for the project was successful in qualitatively and quantitatively analyze the compounds of interest with limit of detection ranging between 0.33–11 μg/L (ppb) in various water sources.

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