Spelling suggestions: "subject:"ambient ionization"" "subject:"embient ionization""
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Využití ambientních ionizačních technik v hmotnostní spektrometrii / The use of ambient ionization techniques in mass spectrometryRejšek, Jan January 2013 (has links)
Keywords: ambient ionization techniques; mass spectrometry; desorption electrospray ionization; desorption atmospheric pressure photoionization; thin layer chromatography; lipids, mass spectrometry imaging Ambient ionization technique in mass spectrometry is an ionization, which carries out in open space outside the machine and which does not require any, or only a minimal sample pretreatment. DESI (desorption electrospray ionization) and DAPPI (desorption atmospheric pressure photoionization) equipped with software control of the spray emitter position for analysis of low molecular organic compounds were investigated in this thesis. These methods use a spray of solvents for desorption and ionization molecules from solid substrate. Conditions for the successful analysis of phospholipids, wax esters and some other compounds were developed. Ambient ionization techniques were quantitatively compared. The application was HPTLC/DESI-MS of lipid's mixture and HPTLC/DAPPI-MS of vernix caseosa. DAPPI-MS was applied for the analysis of termites of Prorhinotermes genus (Isoptera, Rhinotermitidae). Pilot experiments of two dimensional analysis and mass spectrometry imaging were realized.
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Utilization of Mass Spectrometry to Characterize, Image, and Quantify Small MoleculesHilary Brown (8081510) 04 December 2019 (has links)
Ambient ionization techniques, such as nanoDESI and nanoESI, allow for the direct analysis of complex samples under atmospheric pressure with no sample pretreatment. These ionization techniques are utilized for a variety of applications, including lipidomics, online reactions and imaging of small molecules. Nanoelectrospray ionization (nanoESI) is an ionization technique that is similar to electrospray ionization (ESI) but uses smaller sample volumes. NanoESI can be used for complex biological sample analysis and when coupled with online photochemical reactions, such as the Paternò-Büchi (PB) reaction, structural information about lipids can be determined. Likewise, nanoDESI is another ambient ionization technique that employs the ESI mechanism but incorporates online liquid extraction of analytes. This technique is easily incorporated to mass spectrometry imaging (MSI) to provide spatial localization of biomolecules in tissues. Additionally, nanoDESI allows for tunable solvent extraction and online derivatization reactions. These techniques were used to determine structural information of neutral lipids, to image lipids from different developmental stages of lung tissue, and to image and quantify small molecule drugs and metabolites in tissue.
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Microdroplets: Chemistry, Applications and Manipulation Using Ionization Sources and Mass SpectrometryKiran S Iyer (6833102) 04 December 2019
There is widespread use of ionization sources (ambient and non-ambient)
for a variety of applications. More recently, charged microdroplets generated
by electrospray ionization and paper spray have been used to conduct chemistry
at faster rates compared to bulk volumes. Uncharged droplets such as those
generated by the Leidenfrost technique have also been used to explore chemistry
and study the degradation of drugs in an accelerated manner. These
microdroplets serve as reaction vessels in which in which some reactions are
known to occur at accelerated rates. Such chemistry can be particularly useful
in pharmaceutical settings to rapidly synthesize small amounts of materials in
relatively short amount of time. Additionally, microdroplets may also be used
to perform high throughput screening analysis. While several parameters
influencing the rate of reaction in microdroplets have been explored (such as
spray distance and reagent concentration), the mechanism of reaction
acceleration has not been probed to a significant extent. A major portion of my
dissertation describes the use of charged and uncharged microdroplets to
perform quick chemistry, guide microfluidic synthesis of drugs such as diazepam,
perform scale up of copper catalyzed C-O and C-N coupling reactio<a></a>ns and screen reaction conditions for pharmaceutically
relevant reactions such as the Suzuki cross-coupling reaction. Additionally,
work discussed here also describes development and use of existing techniques
such as structured illumination microscopy to measure droplet sizes, explore
the role of distances on droplet size, and study the effect of surfactants on
the rate of reactions in microdroplets generated by nano-electrospray
ionization. A mathematical model to understand the mechanism of increased
reaction rates in microdroplets has also been presented. Additionally, this
dissertation also describes ways to manipulate ions in air using various
designs of 3D-printed electrodes that operate with DC potentials only and which
can be easily coupled with nano-electrospray ionization sources to transmit
ions over long distances
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Detection and Quantitation of Hazardous Chemicals in Environmental Matrices using Paper Spray Mass SpectrometryDowling, Sarah Naciye 08 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Paper spray mass spectrometry (PS-MS) is an ambient ionization technique that has been proven useful in many types of investigative analyses. However, the use of this technique with regards to environmental samples has been largely unexplored since the technique’s development. In this work, paper spray mass spectrometry was utilized to detect and quantify compounds for environmental, forensic and chemical defense applications. Due to the sensitive nature of some projects, the work was split into two volumes. Volume 1 focuses on the detection of pharmaceuticals in soil using paper spray (Chapter 2) and the detection of chemical warfare agent (CWA) simulants and CWA hydrolysis products (Chapter 3). Volume 2 focuses on the detection and quantitation of fentanyl analogs in environmental matrices. Chapter 5 focuses on the rapid analysis of fentanyl analogs in soil matrices. The following chapter evaluates the ability of PS-MS to detect low concentrations of fentanyl analogs in water (Chapter 6). Throughout this work, paper spray has proven to be an effective, rapid alternative to chromatography for the analysis of environmental samples.
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<b>Profiling Phosphatidylethanol Analogs in Dried Blood Spot Samples Using Quadrupole Ion Trap Mass Spectrometry</b>Harmeet Kaur Chohan (18010966) 18 July 2024 (has links)
<p dir="ltr">Phosphatidylethanol (PEth) species are emerging as promising biomarkers for alcohol consumption due to their specificity and stability in biological samples. This thesis employs a quadrupole ion trap mass spectrometer to comprehensively profile 25 PEth analogs in dried blood spot (DBS) samples. The study adopts a semi-quantitative approach utilizing tandem mass spectrometry (MS/MS) to assess relative PEth analog abundances based on ion intensities without inducing fragmentation except that declustering is achieved. This method provides rapid data acquisition compared to absolute concentration determinations, with the potential to provide additional insights into individual metabolic and/or alcohol consumption patterns.</p><p dir="ltr">Initial analysis focuses on precursor ion intensities at unit mass resolution, revealing distinctive distribution patterns of PEth analogs across eight patient samples. Utilizing a heatmap generated from PEth analysis, significant patterns and similarities were identified among certain patient groups. Patient 2 and Patient 8 exhibit similar PEth profiles, while Patient 3, Patient 4, and Patient 5 form another group with comparable PEth analog intensities. Similarly, Patient 6 and Patient 7 also show analogous profiles, whereas Patient 1 stands out with a distinctly unique PEth profile. These observed groupings indicate that, despite the variability in individual responses to alcohol consumption, there are commonalities that can be leveraged to form supergroups based on PEth analysis.</p><p dir="ltr">Subsequent MS/MS analysis elucidates the structural diversity of the top five most abundant PEth analogs (<i>m/z </i>723.5, 751.5, 753.5, 773.5, and 775.5) by fragmenting isolated ions and recording product ion spectra. This approach facilitates the identification of multiple isomeric PEth molecules at specific precursor <i>m/z</i> values, enhancing the characterization of PEth species.</p><p dir="ltr">Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) are employed to interpret MS/MS data, revealing distinct clustering patterns among patient samples based on their PEth profiles. These analyses highlight the discriminatory potential of PEth analogs in delineating alcohol consumption behaviors within a limited cohort.</p><p dir="ltr">Despite limitations related to sample size and cohort specificity, this study underscores the utility of LTQ mass spectrometry in rapid and comprehensive PEth analog profiling. The findings contribute to validating PEth species as reliable biomarkers for alcohol consumption, with implications for clinical diagnostics and forensic applications.</p>
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Development of Paper-Based Immunoassay and Reaction Screening Platforms for Direct Mass Spectrometry Detection under Ambient ConditionLee, Suji January 2021 (has links)
No description available.
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Development of Substrate-based Ambient Ionization Techniques for Direct Sampling by Mass SpectrometryJackson, Sierra January 2021 (has links)
No description available.
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LASER ELECTROSPRAY MASS SPECTROMETRY: INSTRUMENTATION AND APPLICATION FOR DIRECT ANALYSIS AND MOLECULAR IMAGING OF BIOLOGICAL TISSUEShi, Fengjian January 2017 (has links)
This dissertation elucidates the instrumentation and application of a hybrid ambient ionization source, laser electrospray mass spectrometry (LEMS), for the direct analysis and molecular imaging of biological tissue without matrix deposition. In LEMS, laser pulses from a Ti:Sapphire laser amplifier (60 fs, 800 nm, and 1 mJ) interact with surface analytes and transfer them from the condensed phase into the gas phase without the requirement of either exogenous matrix or endogenous water in the sample. The laser vaporized analytes are captured and ionized by an electrospray source, and finally detected by a mass analyzer. It was found that a turn-key, robust femtosecond fiber laser with longer wavelength, longer duration, and lower pulse energy at 1042 nm, 425 fs, and 50 µJ, respectively, provided comparable results with the Ti:Sapphire laser. Vaporization of intact, dried or aqueous cytochrome c and lysozyme samples was demonstrated by the fiber laser. A charge states distribution at lower charge states indicating folded conformation of proteins and the hemoglobin α subunit-heme complex from whole blood was observed. Endogenous anthocyanins, sugars, and other metabolites were detected and revealed the anticipated metabolite profile for the flower petal and leaf samples by the fiber laser. Phospholipids, especially phosphatidylcholine, were identified from a fresh mouse brain section sample. These lipid features were suppressed in both the fiber laser and Ti:Sapphire LEMS measurement in the presence of optimal cutting temperature compounds which are commonly used in animal tissue cryosectioning. This dissertation also details the design of an automated mass spectrometry imaging source based on the Ti:Sapphire LEMS. The laser, translation stage, and mass analyzer are synchronized and controlled using a customized user interface to enable step-by-step scanning of the area of interest on a given tissue sample. The imaging source is coupled with a high resolution accurate mass quadrupole time-of-flight (QTOF) mass analyzer with tandem mass analysis capability. A lateral resolution of 60 µm was demonstrated on a patterned ink film by LEMS imaging. Plant metabolites including sugar and anthocyanins were directly imaged from a leaf sample. Small metabolites, lipids and proteins were simultaneously imaged from a single tissue section of a pig liver sample. Biomarkers of blood-brain barrier damage and traumatic brain injury (TBI) that occurred during the injury were detected and imaged from a TBI mouse brain. The loading values from principal component analysis (PCA) were shown to be useful for identification of features of interest from the large LEMS imaging dataset. / Chemistry
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Detection and Quantitation of Hazardous Chemicals in Environmental Matrices using Paper Spray Mass Spectrometry: Volume 2Sarah Dowling (6944351) 16 October 2019 (has links)
<p>Paper spray mass spectrometry (PS-MS) is an ambient ionization technique that has been proven useful in many types of investigative analyses. However, the use of this technique with regards to environmental samples has been largely unexplored since the technique’s development. In this work, paper spray mass spectrometry was utilized to detect and quantify compounds for environmental, forensic and chemical defense applications. Due to the sensitive nature of some projects, the work was split into two volumes. Volume 1 focuses on the detection of pharmaceuticals in soil using paper spray (Chapter 2) and the detection of chemical warfare agent (CWA) simulants and CWA hydrolysis products (Chapter 3). Volume 2 focuses on the detection and quantitation of fentanyl analogs in environmental matrices. Chapter 5 focuses on the rapid analysis of fentanyl analogs in soil matrices. The following chapter evaluates the ability of PS-MS to detect low concentrations of fentanyl analogs in water (Chapter 6). Throughout this work, paper spray has proven to be an effective, rapid alternative to chromatography for the analysis of environmental samples. </p>
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Development and Applications of Contained Ionization Sources for Direct Complex Mixture Analysis by Mass SpectrometryKulyk, Dmytro S. 02 October 2019 (has links)
No description available.
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