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Articles 1 - 12 of 12
Full-Text Articles in Analytical Chemistry
Uhplc/Ft-Ms Non-Targeted Screening Approach For Biomass Burning Organic Aerosol And Liquid Smoke As Biomass Burning Organic Aerosol Surrogate, D.M.R. Thusitha Dinusha Kumarihami Divisekara
Uhplc/Ft-Ms Non-Targeted Screening Approach For Biomass Burning Organic Aerosol And Liquid Smoke As Biomass Burning Organic Aerosol Surrogate, D.M.R. Thusitha Dinusha Kumarihami Divisekara
Dissertations, Master's Theses and Master's Reports
Biomass combustion contributes a large amount of aerosol particles to the atmosphere impacting the climate system and human health. Identifying the molecular composition of biomass burning organic aerosol (BBOA) is challenging because of its complex nature. Liquid chromatography mass spectrometric non-targeted screening (NTS) methods provide a comprehensive analysis. However, the instrumentation and data analysis are challenging due to the extreme complexity of environmental samples. In the first part of this study, we implemented a new LC/FT-MS data processing approach by combining existing open-source data processing tools, MZmine2.53 and MFAssignR. The method's validity was checked using the standard polyacrylic acid (PAA) …
High-Resolution Molecular Characterization Of Complex Environmental Mixtures: Aquatic Dissolved Organic Matter And Wildfire-Influenced Aerosol, Amna Ijaz
Dissertations, Master's Theses and Master's Reports
The natural environment is replete with organic matter of varying complexities. Whether it is particulate material in the atmosphere, decades old organic matter trapped within glaciers, or biological debris flowing with rivers and streams, natural organic matter (NOM) is exquisitely complex. High-resolution mass spectrometry allows us to have a glimpse of the molecular composition of NOM and delineate the elemental compositions of thousands of chemical species that form it. In this dissertation, the overarching aim was to explore the molecular diversity of complex mixtures from two sources: Surface water and atmospheric organic aerosol. The first objective of this dissertation was …
Determination Of Molecular Markers Of Vaccinium Berry Standard Reference Materials Through Differential Analysis With Ultrahigh Resolution Lc/Ms, Abby Mikolitis
Determination Of Molecular Markers Of Vaccinium Berry Standard Reference Materials Through Differential Analysis With Ultrahigh Resolution Lc/Ms, Abby Mikolitis
Dissertations, Master's Theses and Master's Reports
Blueberries and cranberries have vastly different flavor profiles despite both being a part of the Vaccinium genus. Their high content of phenolics makes them subjects of interest in preventative medicine, especially research in illnesses such as heart disease and cancer. Analysis has primarily focused on the identification and characterization of polyphenols, primarily anthocyanins which are a subclass of polyphenols, with ultra-high performance liquid chromatography coupled with electrospray ionization high resolution mass spectrometry (UHPLC-ES/HRMS). This study aims to develop a novel method of non-targeted UHPLC-ES/MS analysis with post processing and formula assignment performed with MZmine 2.53 and MFAssignR software tools. Pairing …
Cobalt, Molybdenum, And Nickel Complexes, Natural Zeolites, Epoxidation, And Free Radical Reactions, Nicholas K. Newberry
Cobalt, Molybdenum, And Nickel Complexes, Natural Zeolites, Epoxidation, And Free Radical Reactions, Nicholas K. Newberry
Dissertations, Master's Theses and Master's Reports
Chapter 2 is based on the synthesis and study of the compounds of the bidentate ligand ((5-phenyl-1H-pyrazol-3-yl)methyl)phosphine oxide with molybdenum and cobalt as the transition metal. The complexes were analyzed via FTIR, NMR, UV-Vis, Fluorescence Spectroscopy, TGA, DFT, and XRD. Chapter 3 resulted in the synthesis of the complexes [Ni(II)SSRRL](PF6)2 and [Ni(II)SRSRL](Cl)(PF6) of which [Ni(II)SRSRL](Cl)(PF6) had not been previously analyzed. Both products were analyzed via FTIR, NMR, UV-Vis, CV, DFT, and XRD. Chapter 5 contains the results of the characterization and modification of 4 natural zeolites (AZLB-Na, AZLB-Ca, NM-CA, NV-Na) from the United States in an attempt to increase the …
Ratiometric Near-Infrared Fluorescent Probes For The Sensitive Detection Of Intracellular Ph And Bio-Thiols In Live Cells, Shuai Xia
Dissertations, Master's Theses and Master's Reports
In the past twenty years, fluorescence sensing and imaging based on fluorescent probes has been developed as an imperative technique due to the merits including excellent sensitivity, operational simplicity, instant time effectiveness and outstanding selectivity in the research areas such as mineralogy, gemology, biological medicine, materials and environmental engineering. Protons act as a significant role in a variety of pathological and physiological processes, and there are obvious differences in the pH among organelles: the pH in lysosomes is acid within the range of 4.5–5.5, whereas mitochondrial pH is basic that can be as high as 8.0. Abnormal intracellular pH is …
Near-Infrared Fluorescent Probes For Sensitive Determination Of Lysosomal & Mitochondrial Ph In Live Cells, Wafa Mazi
Dissertations, Master's Theses and Master's Reports
Varied intracellular pH levels are critical for various physiological processes such as enzymatic activity, cell proliferation and apoptosis, ion transport, and muscle contraction. Cellular compartments, like lysosomes, must retain an acidic environment (pH ~ 4.5) to activate hydrolytic enzymes necessary for the breakdown of large biomolecules. Another cellular organelle, the mitochondria, provides the cell with energy and must retain an alkalis environment (pH ~ 8.0) for proper function. Substantial lysosomal and mitochondrial pH deviation is associated with cellular dysfunction and disease. Therefore, the precise detection of lysosomal and mitochondrial pH is essential to provide a better understanding of cellular physiological …
Method Considerations For Compound Identification In Complex Mixtures Using Electrospray Ionization Ultrahigh Resolution Mass Spectrometry, Tyler Leverton
Method Considerations For Compound Identification In Complex Mixtures Using Electrospray Ionization Ultrahigh Resolution Mass Spectrometry, Tyler Leverton
Dissertations, Master's Theses and Master's Reports
Biomass burning aerosols are highly complex organic mixtures of thousands of components with consequences for global climate. Complex mixture component identification requires accurate mass measurement capability to separate components on a milli-Dalton scale, frequently using ultrahigh resolution mass spectrometry with electrospray ionization. Certain sample preparations and the ionization process may introduce artifacts that obscure the composition of the sample. Two method considerations were explored using isotopically labeled 15NH4OH and MeOH-d3 to track artifact formation in biomass burning samples. Informatics techniques and a custom molecular formula assignment software were used to identify the isotopic atoms in artifact …
Molecular Characterization Of Free Tropospheric Organic Aerosol And The Development Of Computational Tools For Molecular Formula Assignment, Simeon Schum
Dissertations, Master's Theses and Master's Reports
Organic aerosol affects human health and climate. These effects are largely determined by the composition of the organic aerosol, which is a complex mixture of species. Understanding the complexity of organic aerosol is critical to determining its effect on human health and climate. In this study, long range transported organic aerosol collected at the Pico Mountain Observatory was analyzed using ultrahigh resolution mass spectrometry. Organic aerosol transported in the free troposphere had an overall lower extent of oxidation than aerosol transported in the boundary layer. It was hypothesized that the lower oxidation was related to a more viscous phase state …
Extreme Molecular Diversity In Biomass Burning Atmospheric Organic Aerosol Observed Through Ultrahigh Resolution Mass Spectrometry, Matthew Brege
Extreme Molecular Diversity In Biomass Burning Atmospheric Organic Aerosol Observed Through Ultrahigh Resolution Mass Spectrometry, Matthew Brege
Dissertations, Master's Theses and Master's Reports
Ambient atmospheric aerosol is ubiquitous in the atmosphere, originating from a variety of natural and man-made sources. These microscopic particles have profound impacts on the global climate system as well as human health. The organic fraction of atmospheric aerosol is an extremely complex mixture which is not yet fully characterized. These unknown organic aerosol species contribute to the uncertainty in the effect of aerosol on climate and uncertainty in overall ambient aerosol toxicity. Light absorbing organic aerosol can interact with incoming solar radiation and contribute to atmospheric heating; however, the source apportionment and overall fate of these absorbing organic aerosol …
Influence Of Magnetic Nanoparticles And Magnetic Stress On An Ionic Liquid Electrospray Source, Kurt Joseph Terhune
Influence Of Magnetic Nanoparticles And Magnetic Stress On An Ionic Liquid Electrospray Source, Kurt Joseph Terhune
Dissertations, Master's Theses and Master's Reports
Two electrospray sources were developed to operate on an ionic liquid ferrofluid; one source was a pressure‑fed capillary electrospray source and the other was a novel electrospray source which used a magnetically‑induced instability to produce a peak from which an electric field could extract electrospray. Multiple characteristics of electrospray operation were examined for both sources using faraday plates/cups, a quartz crystal microbalance, a retarding potential analyzer, and a time-of-flight mass spectrometer. The ILFF electrosprays for a capillary source were shown to operate in a mixed ion/droplet regime. The mass flow of the electrospray beam was primarily transported by larger particles …
Design And Development Of Bodipy-Based Fluorescent Probes For Sensing And Imaging Of Cyanide, Zn (Ii) Ions, Lysosomal Ph And Cancer Cells, Jingtuo Zhang
Dissertations, Master's Theses and Master's Reports - Open
BODIPY (4,4-Difluoro-3a,4a-diaza-s-indacene) dyes have gained lots of attention in application of fluorescence sensing and imaging in recent years because they possess many distinctive and desirable properties such as high extinction coefficient, narrow absorption and emission bands, high quantum yield and low photobleaching effect. However, most of BODIPY-based fluorescent probes have very poor solubilities in aqueous solution, emit less than 650 nm fluorescence that can cause cell and tissue photodamages compared with bio-desirable near infrared (650-900 nm) light. These undesirable properties extremely limit the applications of BODIPY-based fluorescent probes in sensing and imaging applications. In order to overcome these drawbacks, we …
Ionic Liquid Extraction Unveils Previously Occluded Humicbound Iron In Peat Porewater, Timothy J. Veverica
Ionic Liquid Extraction Unveils Previously Occluded Humicbound Iron In Peat Porewater, Timothy J. Veverica
Dissertations, Master's Theses and Master's Reports - Open
Extracellular iron reduction has been suggested as a candidate metabolic pathway that may explain a large proportion of carbon respiration in temperate peatlands. However, the o-phenanthroline colorimetric method commonly employed to quantitate iron and partition between redox species is known to be unreliable in the presence of humic and fulvic acids, both of which represent a considerable proportion of peatland dissolved organic matter. We propose ionic liquid extraction as a more accurate iron quantitation and redox speciation method in humic-rich peat porewater. We evaluated both o-phenanthroline and ionic liquid extraction in four distinct peatland systems spanning a gradient of physico-chemical …