Complex Mixture Analysis Using Time of Flight Mass Spectrometry and Comprehensive Gas Chromatography PDF Download
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Author: Jacqueline Fiona Hamilton
Publisher:
ISBN:
Category :
Languages : en
Pages : 472
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Book Description
Author: Jacqueline Fiona Hamilton
Publisher:
ISBN:
Category :
Languages : en
Pages : 472
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Author: Amanda Elizabeth Moses Sinha
Publisher:
ISBN:
Category : Gas chromatography
Languages : en
Pages : 410
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Author: Brooke C. Reaser
Publisher:
ISBN:
Category :
Languages : en
Pages : 172
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Book Description
Gas chromatography is a powerful separation technique that alone, and when coupled with mass spectrometric detection, can provide detailed information regarding the chemical composition of complex mixtures. Advanced chemometric algorithms are often applied to the data generated from these gas chromatographic separations in order to glean additional meaningful information from large and complex data sets. This dissertation presents several research investigations conducted on the development, optimization, application and study of several chemometric algorithms applied to one- and two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (TOFMS). The two-dimensional mass cluster method and principal component analysis (PCA) were applied to a non-targeted investigation of the stable-isotope incorporation of metabolites present in the metabolome of the methylotrophic bacteria Methylobacterium extorquens AM1 using gas chromatography time-of-flight mass spectrometry (GC-TOFMS). The area under the curve (AUC) of receiver operating characteristic (ROC) curves were used as quantitative metrics for the optimization of the tile-based Fisher ratio method using diesel fuel spiked with native and non-native analytes using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC × GC – TOFMS). This optimized algorithm was then applied to a process analytical chemistry (PAC) investigation into the source of catalyst yield reduction in an industrial polymerization plant. Finally, a GC-TOFMS simulation-based study determined the chemometric limit of resolution for deconvoluting analytes using multivariate curve resolution alternating least squares (MCR-ALS) and compared the results to expected theory surrounding the probability of peak overlap.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 233
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Author: Adam Jeremiah Schubert
Publisher:
ISBN:
Category : Analytical chemistry
Languages : en
Pages : 386
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Author: Sarah Elizabeth Prebihalo
Publisher:
ISBN:
Category :
Languages : en
Pages : 151
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Book Description
Comprehensive two-dimensional gas chromatography (GCxGC) coupled with time-of-flight mass spectrometry (TOFMS) is a powerful analytical technique capable of separating complex mixtures, providing valuable information about the chemical composition of samples. However, the inherent data density associated with three-dimensional data provides a unique challenge to analytical chemists. As a result, significant effort has been invested in utilizing advanced chemometrics to glean meaningful information about samples from large and complex data sets. Herein, this dissertation introduces several investigations conducted on optimizing separation conditions to be amenable to chemometric deconvolution algorithms as well as the development, study, and application of advanced chemometric techniques applied to GCxGC-TOFMS data. To begin, the metric trilinear deviation ratio (TDR) is utilized to study the impact of experimental parameters such as column selection and modulation period, PM, on the quantitative accuracy of parallel factor analysis (PARAFAC) deconvolution. TDR scales with increasing change in second dimension retention time, delta2tR, associated with pseudo-isothermal conditions on the second dimension, 2D, and quantitative accuracy decreases as TDR increases. Two column sets were utilized with varying film thickness on the first column, 1D, and each column set was studied using two PM for a total of 4 experiments. It was reported that using 1D columns with larger film thicknesses allows the analyst to employ a shorter PM, in turn lowering the delta2tR, leading to higher quantitative accuracy. Many GCxGC-TOFMS studies relate to identifying class distinguishing analytes and can be tedious when performed manually. Fortunately, the use of discovery-based chemometric tools such as principal component analysis (PCA) and Fisher ratio (F-ratio) analysis has increased in popularity as less time-intensive and automated techniques for untargeted analyses. To begin, this dissertation will investigate mass channel purity obtained via the tile-based F-ratio algorithm using diesel fuel spiked with non-native analytes using GCxGC-TOFMS. The F-ratio algorithm, considered a supervised discovery technique because class membership is known a priori, was first used to "discover" the spiked non-native analytes. Then, using a novel signal ratio (S-ratio) algorithm, the mass channel selectivity information output by the F-ratio method was studied using three statistical metrics: null distribution analysis, p-value, and lack-of-fit (LOF). The result of this investigation revealed that a mass channel has a high likelihood of being pure when its p-value and LOF are sufficiently low. Finally, F-ratio analysis was applied to a dataset including patients with an anterior cruciate ligament (ACL) injury to discover potential biomarkers of post-traumatic osteoarthritis (PTOA) post-injury. Standard F-ratios are calculated by the between class variance divided by the sum of the within-class variance, scaling up as the between class variance increases and the within-class variance remains sufficiently small. However, many biological studies involve significant biological variance (~30%) that may not be associated with disease state or injury severity, etc. Herein, the standard tile-based F-ratio algorithm was modified to use only the within-class variance associated with control samples. It was expected that the control class contained less within-class variance relative to the patient class, due to the expectation that some patient samples would be associated with increased severity of injury or the presence of coexisting conditions. Hit lists (metabolites discovered via F-ratio) from standard F-ratio and control-normalized F-ratio were studied and directly compared to establish a comprehensive metabolome of potential biomarkers for PTOA development post ACL injury. Reported in this dissertation is a discussion on the complementary nature of standard and control-normalized F-ratio, followed by demonstration of class distinguishing metabolites via PCA.
Author: Carlos Andres Manzano
Publisher:
ISBN:
Category : Gas chromatography
Languages : en
Pages : 132
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Book Description
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants and are mostly products of the incomplete combustion of organic material. PAHs are often found in environmental samples as a complex mixture of isomers. In addition, the same sources that produce complex PAH mixtures also produce other poorly characterized mixtures of organic compounds, commonly referred to as an unresolved complex mixture (UCM), that act as matrix interferences in the chromatographic analysis of samples. Conventional one-dimensional chromatographic techniques, such as gas chromatography coupled to mass spectrometry (GC/MS), are not sufficient for the analysis and quantitation of complex PAH mixtures present in environmental samples due to the high degree of overlap in compound vapor pressures, boiling points, and mass spectral fragmentation patterns. Therefore, the separation and quantitation of complex mixtures of individual PAH compounds in environmental samples requires high chromatographic resolution. Comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GCxGC/ToF-MS) was used for this study. GCxGC/ToF-MS uses two different gas chromatographic columns, with different separation mechanisms, for the analysis of complex environmental samples. In theory, the peak capacity in GCxGC/ToF-MS is equivalent to the product of the individual peak capacities of each column used. However, in practice, this is rarely obtained because of the existing correlation between the two GC columns used. This dissertation is a compilation of three studies related to analytical method development for the identification and quantitation of complex PAH mixtures (including parent-PAHs, alkyl-PAHs, oxy-PAHs, nitro-PAHs, thio-PAHs, chloro-PAHs, bromo-PAHs and PAHs with molecular weight higher than 300 Da) that may be present in environmental samples using novel column combinations in GCxGC/ToF-MS. The use of a liquid crystal column (LC-50) in the first dimension, followed by a nano-stationary phase column (NSP-35) in the second dimension, was evaluated for the separation of a standard PAH mixture containing 97 different PAHs. Two standard reference materials purchased from NIST (NIST SRM1650b - Diesel Particulate Matter and NIST SRM1975 - Diesel Extract) were used, after extraction and cleanup, for method validation and comparison between the commonly used non-polar x polar column combination and the LC-50 x NSP-35 column combination with high orthogonality. As part of the method validation, an aliquot of NIST SRM1975 (Diesel extract), without sample cleanup was also analyzed for PAHs, showing that the LC-50 x NSP-35 column combination was accurate (with an average absolute percent difference of approximately 30%) for the identification and quantitation of complex PAH mixtures in environmental samples, with reduced sample preparation prior to analysis. In addition, the LC-50 x NSP-35 column combination was used for the analysis of PAHs sorbed to polystyrene pellets deployed in an urban bay area as passive water samplers because one-dimensional GC/MS was ineffective due to the presence of a strong unresolved complex mixture (UCM) and matrix interferences.
Author: R. P. Philp
Publisher: Elsevier Publishing Company
ISBN:
Category : Biochemical markers
Languages : en
Pages : 316
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Book Description
This is the first collection of biomarker spectra to be published. It comprises two parts: the first discusses the origins of various classes of biomarkers and how they can be applied to petroleum exploration problems. The second and main part of the book contains almost 400 biomarker mass spectra, collected from a wide range of scientific journals. Each spectrum is accompanied by a summary of data, including acquisition conditions, biomarker origin, and authenticity of the data.
Author: Joy Renee Klosterman
Publisher:
ISBN:
Category : Acid-forming emissions
Languages : en
Pages : 150
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Book Description
Author: O. David Sparkman
Publisher: Academic Press
ISBN: 0080920152
Category : Science
Languages : en
Pages : 633
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Book Description
The second edition of Gas Chromatography and Mass Spectrometry: A Practical Guide follows the highly successful first edition by F.G. Kitson, B.S. Larsen, and C.N. McEwen (1996), which was designed as an indispensible resource for GC/MS practitioners regardless of whether they are a novice or well experienced. The Fundamentals section has been extensively reworked from the original edition to give more depth of an understanding of the techniques and science involved with GC/MS. Even with this expansion, the original brevity and simple didactic style has been retained. Information on chromatographic peak deconvolution has been added along with a more in-depth understanding of the use of mass spectral databases in the identification of unknowns. Since the last edition, a number of advances in GC inlet systems and sample introduction techniques have occurred, and they are included in the new edition. Other updates include a discussion on fast GC and options for combining GC detectors with mass spectrometry. The section regarding GC Conditions, Derivatization, and Mass Spectral Interpretation of Specific Compound Types has the same number of compound types as the original edition, but the information in each section has been expanded to not only explain some of the spectra but to also explain why certain fragmentations take place. The number of Appendices has been increased from 12 to 17. The Appendix on Atomic Masses and Isotope Abundances has been expanded to provide tools to aid in determination of elemental composition from isotope peak intensity ratios. An appendix with examples on "Steps to follow in the determination of elemental compositions based on isotope peak intensities" has been added. Appendices on whether to use GC/MS or LC/MS, third-party software for use in data analysis, list of information required in reporting GC/MS data, X+1 and X+2 peak relative intensities based on the number of atoms of carbon in an ion, and list of available EI mass spectral databases have been added. Others such as the ones on derivatization, isotope peak patterns for ions with Cl and/or Br, terms used in GC and in mass spectrometry, and tips on setting up, maintaining and troubleshooting a GC/MS system have all been expanded and updated. - Covers the practical instruction necessary for successful operation of GC/MS equipment - Reviews the latest advances in instrumentation, ionization methods, and quantitation - Includes troubleshooting techniques and a variety of additional information useful for the GC/MS practitioner - A true benchtop reference - A guide to a basic understanding of the components of a Gas Chromatograph-Mass Spectrometer (GC-MS) - Quick References to data interpretation - Ready source for information on new analyses
