Characterization of Dissolved Organic Matter in Wastewater Using Liquid Chromatography-high Resolution Mass Spectrometry PDF Download
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Author: Yaroslav Verkh
Publisher:
ISBN:
Category :
Languages : en
Pages : 140
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Book Description
Individual hazardous chemicals and substance mixtures with synergistic toxicity ef-fects occur in the dissolved organic matter (DOM) of wastewater and negatively im-pact human health. Yet a large number of chemicals and their treatment by-products in wastewater makes the tracking of individual compounds nearly impossible and de-mands new analytical strategies. The thesis describes the development and evaluation of non-targeted and suspect anal-ysis methods aimed at the transformation of DOM and micro-contaminants of interest during wastewater treatment using liquid chromatography-high-resolution mass spec-trometry (LC-HRMS) data. On one hand, a non-targeted method to track transformations of DOM in a multiphase wastewater treatment using LC-HRMS data was developed. LC-MS signals were ex-tracted, aligned, and had their isotopologues clustered and elemental composition pre-dicted using open license software MZmine 2 in a way that conceptually prioritized the detection of anthropogenic compounds.
Author: Yaroslav Verkh
Publisher:
ISBN:
Category :
Languages : en
Pages : 140
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Book Description
Individual hazardous chemicals and substance mixtures with synergistic toxicity ef-fects occur in the dissolved organic matter (DOM) of wastewater and negatively im-pact human health. Yet a large number of chemicals and their treatment by-products in wastewater makes the tracking of individual compounds nearly impossible and de-mands new analytical strategies. The thesis describes the development and evaluation of non-targeted and suspect anal-ysis methods aimed at the transformation of DOM and micro-contaminants of interest during wastewater treatment using liquid chromatography-high-resolution mass spec-trometry (LC-HRMS) data. On one hand, a non-targeted method to track transformations of DOM in a multiphase wastewater treatment using LC-HRMS data was developed. LC-MS signals were ex-tracted, aligned, and had their isotopologues clustered and elemental composition pre-dicted using open license software MZmine 2 in a way that conceptually prioritized the detection of anthropogenic compounds.
Author: Xianyu Kong
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Dissolved organic matter (DOM) in the ocean is a complex mixture of molecules derived from autochthonous (marine) or allochthonous (terrestrial) origins. DOM plays an important role in marine biogeochemical cycles by attenuating light available for primary production, serving as an energy and nutrient source for heterotrophic communities, regulating the ultraviolet and visible light absorption, undergoing photochemical processing, and acting as a trace metal ligand. DOM in the Central Arctic Ocean (CAO) is influenced by increased freshwater input and associated terrestrial materials in recent decades due to rapid climate change. The quantification of DOM sources (terrestrial versus marine) in the water column of the CAO is not well constrained. Few studies have systematically investigated the seasonality and spatial variability of DOM by combining optical and molecular-level analytical techniques in the CAO, especially during winter. State of the art chemical characterization of DOM is subject to major challenges: Solid phase extraction (SPE) that is often used to desalt and pre-concentrate marine DOM introduces chemical fractionation effects, which limits the comparability between analytical results for original samples and those carried out for SPE-DOM. There is no specific method to quantify fractionation effects, nor specific guidelines to avoid fractionation. Using mass spectrometry, quantitative DOM analyses is challenged by selective ionization of molecules and the large number of unresolved structural isomers that prevent classical external calibration. In the first part of this thesis, a method was developed to quantitatively track optical or chemical fractionation during SPE and investigate the potential mechanisms. We found a decrease in extraction efficiency of dissolved organic carbon (DOC), fluorescence and absorbance, and polar organic substances with increasing carbon loading on the SPE column. As the surface loading of the solid-phase increased, the dominant extraction mechanism shifted from PPL physisorption to increased DOM self-assembly, resulting in optical and chemical fractionation. The relative DOC loading (DOCload) was used to assess the carbon loading during SPE, and a double sigmoid model was applied to our online permeate fluorescence data as a function of DOCload, which allowed us to assess the degree of variability induced by DOCload. This finding has ample implications for the future processing and previous interpretation of chemical characteristics in SPE-DOM of aquatic organic matter. For the second part of the thesis, original water samples were acquired from the “Multidisciplinary Drifting Observatory for the Study of Arctic Climate” (MOSAiC) expedition. The water column samples covered a full year (2019 / 2020) and included the regions Amundsen Basin, western Nansen Basin and Yermak Plateau and Fram Strait. Samples were analyzed using optical spectroscopy to determine chromophoric DOM (CDOM) and fluorescent DOM (FDOM). In addition, a new method was applied that used Fourier transform ion cyclotron resonance mass spectrometry hyphenated to high performance liquid chromatography (LC-FTMS). The method allowed DOM analysis in original filtered water and thus avoided the chemical fractionation introduced by SPE. During the MOSAiC expedition, DOC concentrations and CDOM characteristics in the water column were primarily influenced by regional differences. These differences were largely dependent on terrestrially-derived DOM (tDOM) input by the transpolar drift (TPD) as indicative of average 136% and 45% higher aCDOM(350) and DOC concentration, respectively, in the Amundsen compared to the western Nansen Basin and Yermak Plateau, and slightly modified by seasonal changes. Despite the convenient identification of tDOM, optical spectroscopy was not suitable to quantify the contribution of tDOM to bulk DOC or to track sea ice derived DOM in the water column. In contrast, using LC-FTMS, we found quantitative linear correlation between the summed mass peak magnitudes for each sample (intsum) and DOC concentration. By combing LC-FTMS and source identification with optical parameters, we were able to quantify DOM sources (terrestrial versus marine) in the water column: 83% of the summed peak magnitude of all samples could be related to marine or terrestrial sources. tDOM contributed ∼17% (or 8 μmol kg-1) to deep DOC (~2000 m) in the CAO and was more refractory and had a higher state of unsaturation compared to marine DOM. The quantitative characterization of DOM in original seawater from different origin is a major step in the field of research. It provides a unique and new insight into the molecular changes in marine DOM composition and an improved understanding of the terrestrial DOM distribution in the CAO.
Author: Vanessa-Nina Roth
Publisher:
ISBN:
Category :
Languages : en
Pages : 164
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Author: Christopher L. Osburn
Publisher: Frontiers Media SA
ISBN: 2889450813
Category :
Languages : en
Pages : 244
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A substantial increase in the number of studies using the optical properties (absorbance and fluorescence) of dissolved organic matter (DOM) as a proxy for its chemical properties in estuaries and the coastal and open ocean has occurred during the last decade. We are making progress on finding the actual chemical compounds or phenomena responsible for DOM’s optical properties. Ultrahigh resolution mass spectrometry, in particular, has made important progress in making the key connections between optics and chemistry. But serious questions remain and the last major special issue on DOM optics and chemistry occurred nearly 10 years ago. Controversies remain from the non-specific optical properties of DOM that are not linked to discrete sources, and sometimes provide conflicting information. The use of optics, which is relatively easier to employ in synoptic and high resolution sampling to determine chemistry, is a critical connection to make and can lead to major advances in our understanding of organic matter cycling in all aquatic ecosystems. The contentions and controversies raised by our poor understanding of the linkages between optics and chemistry of DOM are bottlenecks that need to be addressed and overcome.
Author:
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Category :
Languages : en
Pages :
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Zeitungsausschnitte.
Author: D. W. H. Rankin
Publisher: John Wiley & Sons
ISBN: 1118462882
Category : Science
Languages : en
Pages : 606
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Book Description
Determining the structure of molecules is a fundamental skill that all chemists must learn. Structural Methods in Molecular Inorganic Chemistry is designed to help readers interpret experimental data, understand the material published in modern journals of inorganic chemistry, and make decisions about what techniques will be the most useful in solving particular structural problems. Following a general introduction to the tools and concepts in structural chemistry, the following topics are covered in detail: • computational chemistry • nuclear magnetic resonance spectroscopy • electron paramagnetic resonance spectroscopy • Mössbauer spectroscopy • rotational spectra and rotational structure • vibrational spectroscopy • electronic characterization techniques • diffraction methods • mass spectrometry The final chapter presents a series of case histories, illustrating how chemists have applied a broad range of structural techniques to interpret and understand chemical systems. Throughout the textbook a strong connection is made between theoretical topics and the real world of practicing chemists. Each chapter concludes with problems and discussion questions, and a supporting website contains additional advanced material. Structural Methods in Molecular Inorganic Chemistry is an extensive update and sequel to the successful textbook Structural Methods in Inorganic Chemistry by Ebsworth, Rankin and Cradock. It is essential reading for all advanced students of chemistry, and a handy reference source for the professional chemist.
Author: Carla Jean Steinbring
Publisher:
ISBN:
Category :
Languages : en
Pages : 71
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Author: Jeffrey P. LeClair
Publisher:
ISBN:
Category :
Languages : en
Pages : 216
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Author: Tracy Michelle Quan
Publisher:
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Category : Carbon
Languages : en
Pages : 212
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(Cont.) This new separation protocol utilized various chromatographic techniques, including cation exchange chromatography and high- pressure liquid chromatography (HPLC) using C18 and strong cation exchange (SCX) columns. Six amino acids were isolated from a HMWDOM sample with sufficient purity and quantity for radiocarbon analysis. These amino acids had a range of A'4C values, from 121%o to -454%o. The final section investigates biological controls on the dissolved organic nitrogen (DON) pool. Total hydrolyzable amino acids (THAA), and nucleic acids were measured for four incubations: a control incubation, a grazer added incubation, a zero virus incubation, and a 10 times virus incubation. Comparison to the control showed THAA and nucleic acid release were influenced by viruses but not grazers.
Author: Neal Ken Arakawa
Publisher:
ISBN:
Category :
Languages : en
Pages : 151
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The primary objective of this thesis was to combine a chemical degradation technique together with an analytical framework centered primarily around gas chromatography (GC) to more fully interrogate the composition of aquatic dissolved organic matter (DOM). Previous studies had suggested that aliphatic compounds could represent a significant fraction of refractory organic matter isolated by solid phase extraction (SPE). These studies had also uncovered the vast complexity of DOM. Gas chromatography coupled to mass spectrometry provides superior separation capability and is ideal for examining complex mixtures of lipid-derived molecules. As such I sought to develop a comprehensive GC analysis methods to provide molecular level information for DOM isolated by solid phase extraction (SPE) onto a hydrophobic resin- PPL (Agilent Bond Elut). In Chapter II, a comprehensive chemical reduction procedure was developed and first applied to the environmental DOM standard Suwannee River Fulvic Acid (SRFA) as a proxy for marine DOM. The resulting hydrocarbons were amenable to comprehensive gas chromatography time-of-flight mass spectrometry (GCxGC-TOF-MS), and effectively resolved into multiple series of alicyclic, unsaturated compounds. This was the first direct demonstration of the isomeric complexity of aquatic DOM. Similar alicyclic compounds were recovered from the reduction of terrestrial source material, implicating resin acids and sterols as potential precursors of SRFA. In Chapter III the reduction process was applied to marine surface DOM from the Scripps Institution of Oceanography Pier, and similar alicylic compounds were found. The GCxGC-TOF-MS identified carbon backbones closely resembling carotenoids, implicating these ubiquitous and highly reactive biomolecules as the source of a significant fraction of DOM accumulating in the marine water column. The structural assignment was supported by the identification of carotenoid derived resonances in two dimensional nuclear magnetic resonance (NMR) spectra, which indicated that these molecules were highly oxidized compared to the parent molecules consistent with their present in DOM. Following up on this work in Chapter IV the carotenoid [beta]-carotene was irradiated with natural sunlight to test the hypothesis that photodegradation was one pathway that converted carotenoids into water-soluble degradation products. The first finding was that the reaction produced a series of compounds identical to compounds isolated from marine DOM. The second important result was that the reaction produced a complex mixture of isomers from a single compound that helps to at least partly explain the compositional diversity in marine DOM. Together, the data in Chapters III and IV allowed us to link a large fraction of DOM to a ubiquitous biomolecule that can now serve as a model for studies examining the formation and fate of DOM that accumulates in the ocean on long timescales. Finally, in Chapter V we sought to examine how the composition of DOM -- both the complex alicyclic fraction and small, polar biomolecules, which are considered a "fresher" signal of biological input -- evolved across a salinity gradient. Although core biochemical classes were present in all regions the data supported in situ production of compositionally similar material rather than mixing across the gradients as proposed in some studies. Together, the chapters in my thesis provide new insight in the composition of dissolved organic matter in marine and terrestrial environments. The thesis also represents the most comprehensive molecular level characterization of DOM isolated by this solid phase extraction method, which is the most commonly used isolation method in the field. My findings also provide an important foundation for future lab-based mechanistic studies of DOM cycling in the marine environment.
