Characterization of Complex Mixtures of the Light Shredder Waste Fraction and Caramelization Processes by Mass Spectrometry PDF Download
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Author: Agnieszka Golon Publisher: ISBN: Category : Languages : en Pages : 161
Book Description
The analysis of complex mixtures is one of the most challenging areas of analytical chemistry. Within this thesis the composition of two complex mixtures of environmental and food origin, such as the light shredder waste fraction and caramel was studied, respectively. In the last few decades, the light shredder waste fraction has attracted much interest due to the scarcity of space and the toxicological properties of some of its contaminants. In this work, gas chromatography with a flame ionization detector (FID) as well as coupled to mass spectrometry with electron impact (EI) and atmospheric pressure chemical ionization (APCI) has been applied to study the composition of the light shredder waste fraction focusing on non-volatile hydrocarbons. GC-APCI with a time of flight mass analyzer was utilized for the first time in order to determine heavy hydrocarbons of n-alkanes standard and the light shredder waste fraction. Adducts, such as [(M-3H)+H2O]+ and [M-H]+ were found to be the most abundant ions up to n-nonadecane (C19H40) and for higher hydrocarbons established by APCI, respectively. In the second part of this thesis, the composition of caramel, one of the mankind'Engineering and Sciences well-known dietary materials, obtained by the heating of carbohydrates, have been studied. Caramel formed by heating of glucose, fructose, galactose, mannose as well as disaccharides, such as sucrose, lactose and maltose using a conceptually novel combination of mass spectrometric techniques have yielded for the first time an unprecedented account of its chemical composition. The analytical strategy employed uses high-resolution mass spectrometry to identify the most abundant molecular formulas followed by a van Krevelen and Kendrick analysis. A resulting structural hypothesis was further substantiated using targeted LC-tandem MS experiments. The caramelization products include oligomers with up to six carbohydrate units produced through an unselective glycosidic bond formation, dehydration products of oligomers losing up to eight water molecules, hydration products of sugar oligomers, disproportionation and aromatic products. In addition, the molecular formulas of compounds responsible for a brown color of caramel were also proposed. The investigation of thermal decomposition products of pure starch and cellulose as model systems followed by the investigation of bread obtained under comparable conditions has been performed. Commercial caramel products and caramel colors (E 150) were compared with studied carbohydrates. Furthermore, understanding of the composition of roasted coffee beans has been improved by the examination of their carbohydrates fraction.
Author: Agnieszka Golon Publisher: ISBN: Category : Languages : en Pages : 161
Book Description
The analysis of complex mixtures is one of the most challenging areas of analytical chemistry. Within this thesis the composition of two complex mixtures of environmental and food origin, such as the light shredder waste fraction and caramel was studied, respectively. In the last few decades, the light shredder waste fraction has attracted much interest due to the scarcity of space and the toxicological properties of some of its contaminants. In this work, gas chromatography with a flame ionization detector (FID) as well as coupled to mass spectrometry with electron impact (EI) and atmospheric pressure chemical ionization (APCI) has been applied to study the composition of the light shredder waste fraction focusing on non-volatile hydrocarbons. GC-APCI with a time of flight mass analyzer was utilized for the first time in order to determine heavy hydrocarbons of n-alkanes standard and the light shredder waste fraction. Adducts, such as [(M-3H)+H2O]+ and [M-H]+ were found to be the most abundant ions up to n-nonadecane (C19H40) and for higher hydrocarbons established by APCI, respectively. In the second part of this thesis, the composition of caramel, one of the mankind'Engineering and Sciences well-known dietary materials, obtained by the heating of carbohydrates, have been studied. Caramel formed by heating of glucose, fructose, galactose, mannose as well as disaccharides, such as sucrose, lactose and maltose using a conceptually novel combination of mass spectrometric techniques have yielded for the first time an unprecedented account of its chemical composition. The analytical strategy employed uses high-resolution mass spectrometry to identify the most abundant molecular formulas followed by a van Krevelen and Kendrick analysis. A resulting structural hypothesis was further substantiated using targeted LC-tandem MS experiments. The caramelization products include oligomers with up to six carbohydrate units produced through an unselective glycosidic bond formation, dehydration products of oligomers losing up to eight water molecules, hydration products of sugar oligomers, disproportionation and aromatic products. In addition, the molecular formulas of compounds responsible for a brown color of caramel were also proposed. The investigation of thermal decomposition products of pure starch and cellulose as model systems followed by the investigation of bread obtained under comparable conditions has been performed. Commercial caramel products and caramel colors (E 150) were compared with studied carbohydrates. Furthermore, understanding of the composition of roasted coffee beans has been improved by the examination of their carbohydrates fraction.
Author: Nadim Hourani Publisher: ISBN: Category : Languages : en Pages : 150
Book Description
The lack of a routine characterization method for non-volatile hydrocarbons has been an ongoing problem preventing mass spectrometry from the analysis of these hydrocarbons within many sources. Non-polar hydrocarbons are still difficult to be detected by mass spectrometry. Although several studies targeted this problem, lack of self-ionization has been limiting the ability of mass spectrometry to examine these hydrocarbons. A novel identification method for saturated straight-chain hydrocarbons in light shredder waste fraction under atmospheric pressure chemical ionization mass spectrometry (APCI-MS) has been developed. Ionization of alkanes under nitrogen gas source favoured hydrogen abstraction producing majorly (M-H)+ ions which are strictly corresponding to their respective series of n-alkanes between n-decane (C10) and n-tetracontane (C40). The method is shown to produce intact gas phase ions of n-alkane in both reference and real life waste samples. APCI-MS2 fragmentation data assisted in the structural verification of the n-alkanes investigated in both standard and waste mixtures. Additionally the total chemical composition of the light shredder waste fraction was translated by the same method. The mass spectrum displayed a bimodal distribution of odd and even mass ions with a molecular weight distribution range of m/z 200-900 Da. Molecular formulas for a 1000 unsaturated hydrocarbon compounds suggested a dehydrogenation process. The molecular masses were plotted on a Kendrick plot which was successfully employed for monitoring sample degradation. Another selection of high mass linear, branched and cyclic hydrocarbons, reported to be notoriously difficult to ionize, were examined during this study. Using optimized APCI conditions all of these analytes could be ionized without the use of an additional ionization aid and without fragmentation. This finding represents a promising step towards extending the applicability of mass spectrometry to complex non-polar hydrocarbon analyses.
Author: Ralf Zimmermann Publisher: John Wiley & Sons ISBN: 3527335102 Category : Science Languages : en Pages : 448
Book Description
Provides comprehensive coverage of laser-induced ionization processes for mass spectrometry analysis Drawing on the expertise of the leading academic and industrial research groups involved in the development of photoionization methods for mass spectrometry, this reference for analytical scientists covers both the theory and current applications of photo-induced ionization processes. It places widely used techniques such as MALDI side by side with more specialist approaches such as REMPI and RIMS, and discusses leading edge developments in ultrashort laser pulse desorption, to give readers a complete picture of the state of the technology. Photoionization and Photo-Induced Processes in Mass Spectrometry: Fundamentals and Applications starts with a complete overview of the fundamentals of the technique, covering the basics of the gas phase ionization as well as those of laser desorption and ablation, pulse photoionization, and single particle ionization. Numerous application examples from different analytical fields are described that showcase the power and the wide scope of photo ionization in mass spectrometry. -The first general reference book on photoionization techniques for mass spectrometry -Examines technologies and applications of gas phase resonance-enhanced multiphoton ionization mass spectrometry (REMPI-MS) and gas phase resonance ionization mass spectrometry (RIMS) -Provides complete coverage of popular techniques like MALDI -Discusses the current and potential applications of each technology, focusing on process and environmental analysis Photoionization and Photo-Induced Processes in Mass Spectrometry: Fundamentals and Applications is an excellent book for spectroscopists, analytical chemists, photochemists, physical chemists, and laser specialists.
Author: Publisher: ISBN: Category : Languages : en Pages : 5
Book Description
The overall objective of this research was to develop and enhance our understanding of the identity of major organic complexant species and their products with metals in aqueous mixtures such as those found in DOE radioactive tank wastes. Our approach to achieving this objective was a series of incremental studies involving cooperative efforts at ORNL and at the University of Minnesota. Investigations at ORNL characterized soft ionization mass spectrometry processes for the complexant species by developing and interpreting positive and negative ion thermospray mass spectrometry (TMS) of some organic complexants and their decomposition products and relating the spectral distributions to gas phase chemistry. This knowledge of the gas phase chemistry can be related to known solution chemistry behavior. At the University of Minnesota liquid chromatography separations on zirconia-based chromatographic supports were studied in 2 order to understand the separation of organic complexants and the products formed by complexants with metals in complex aqueous mixtures. This information was used to define the conditions needed to introduce a simplified chemical stream into the mass spectrometer. Ultimately the knowledge gained from these parallel efforts were combined at ORNL to characterize the complexant species in a multi-component aqueous mixture. The final objective was to develop the analytical capability needed to identify complexant species and to define chemical equilibria for these species in DOE waste streams.
Author: Publisher: ISBN: Category : Languages : en Pages : 5
Book Description
The goal of this project was to expand the range of chemical species that may be detected by membrane introduction mass spectrometry (MIMS) in environmental, and specifically in Mixed Waste, monitoring and characterization applications. Membrane introduction mass spectrometry (MIMS) functions as a near real-time monitor: there is little to no sample preparation and t analysis time is seconds to minutes. MIMS can be implemented as a flow injection technique, where samples, standards, and method blanks can be sequentially analyzed in a continuous fashion. The membrane acts as an interface between the sample (air or water) and the vacuum of the mass spectrometer. Transport of the analyte through the membrane occurs by the process of pervaporation. This process is described by adsorption to the outer surface of the membrane, diffusion through the membrane, and desorption from the inner membrane surface into a helium gas flow or into vacuum. The driving force for this work is the need for a rapid, sensitive, and broadly applicable tool for characterizing organic and metal-containing contaminants in a variety of DOE (and other) waste streams. In all characterization scenarios, a balance must be struck between evaluation of the hazards and their extent at a waste site, and the resources available for the overall mitigation of that risk. In the case of chemically, physically, and geometrically homogeneous waste, the situation is aided by the ability to reasonably assume that any sample collected is representative of the overall site constituents. However, few real environmental challenges are homogeneous. As a result, detailed sampling plans must be prepared, and chemical analyses must be performed on a number of samples in order to identify areas of contamination and assess further options. For many years, the chemical analysis part of this process has been accomplished by delivering the samples to a (typically) physically remote laboratory, where very detailed, and concomitantly expensive (both in time and money), procedures have been applied to the samples to determine their content; Environmental Protection Agency (EPA) methods for analyzing wastes for hazardous chemicals are 3 time-tested and very reliable. However, in many cases both time and resources may be conserved by being able to make survey analyses at the waste site to determine if any or all samples need to be exhaustively characterized by laboratory-based EPA analytical methods. A variety of groups worldwide are working on MIMS as a rapid screening tool for a variety of I applications; please see our review paper for a detailed overview of these efforts. Our primary innovations, developed during this project, have been the optimization of the ion source for environmental analyses and the study of chemically tailored pervaporation membranes for enhanced selectivity and sensitivity.
Author: Agnieszka Golon
Author: Agnieszka Golon
Author: Nadim Hourani
Author: Ralf Zimmermann
Author: Randy J. Arnold
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Author: Narendra Kumar Meruva
Author: Jacqueline Fiona Hamilton
Author: Joy Renee Klosterman