Author: James Janesko
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
High molecular weight -- polycyclic aromatic hydrocarbons (HMW-PAH) are often found where air, water, and soil are subject to higher levels of industrial pollutants. These molecules are environmentally concerning due to their carcinogenic, mutagenic, and tumorigenic propensities. Furthermore, the isomers in this family are challenging to separate due to similar retention parameters, spectroscopic fingerprints, and mass spectral patterns.
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:
Publisher:
ISBN:
Category : Medicine
Languages : en
Pages : 1940
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Book Description
Vols. for 1963- include as pt. 2 of the Jan. issue: Medical subject headings.
Author: National Institute of Standards and Technology (U.S.)
Publisher:
ISBN:
Category :
Languages : en
Pages : 1162
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Book Description
Author: Hamir S. Rathore
Publisher: CRC Press
ISBN: 9780849330056
Category : Science
Languages : en
Pages : 442
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Book Description
Handbook of Chromatography provides a detailed description of significant aspects of polycyclic aromatic hydrocarbons (PAHs). The sources, occurrence, nomenclature, and carcinogenicity of PAHs are covered, and a comprehensive record of data of sample preparation, detection, separation, determination, and characterization of PAHs by liquid chromatography is presented. The book also summarizes extraction and enrichment procedures (e.g., Soxhlet extraction, ultrasonic extraction, liquid-liquid partitioning); presents data from paper chromatography, thin-layer chromatography, high-performance thin-layer chromatography, and electrophoresis of PAHs; and discusses the methodology and applications of extrography in analyzing complex aromatic materials. Handbook of Chromatography also provides a PAHs book directory and a list of suppliers of PAHs and HPLC columns. The volume will be an essential reference for analytical chemists, environmental toxicologists, organic chemists, biomedical specialists, and biotechnicians.
Author: British Carbonization Research Association
Publisher:
ISBN:
Category : Hydrocarbons
Languages : en
Pages :
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Book Description
Author: Prasad L. Polavarapu
Publisher: CRC Press
ISBN: 1315357194
Category : Science
Languages : en
Pages : 298
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Book Description
This book details chiroptical spectroscopic methods: electronic circular dichroism (ECD), optical rotatory dispersion (ORD), vibrational circular dichroism (VCD), and vibrational Raman optical activity (VROA). For each technique, the text presents experimental methods for measurements and theoretical methods for analyzing the experimental data. It also includes a set of experiments that can be adopted for undergraduate teaching laboratories. Each chapter is written in an easy-to-follow format for novice readers, with necessary theoretical formalism in appendices for advanced readers.
Author: Hugh V. Hayes
Publisher:
ISBN:
Category :
Languages : en
Pages : 259
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Book Description
Additional work related to the NPLC fractionation of SRM 1597 included the collection of room-temperature fluorescence spectra for the 21 PAHs with molecular mass (MM) 302 Da known to be in SRM 1597a during reversed-phase liquid chromatography (RPLC) separation. Adding spectral features to a chromatographic run provided the tentative identification of 20 PAHs based on retention times and the presence of 18 were confirmed on the basis of spectral profiles. The advancements in liquid chromatography presented in this dissertation via NPLC fractionation along with RPLC stop-flow fluorescence spectra collection shows potential for becoming routine methodologies for PAC determination in complex environmental samples.
Author: Peter Schreier
Publisher: Walter de Gruyter
ISBN: 3110867850
Category : Science
Languages : en
Pages : 353
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Book Description
Author: Chang-kee Lim
Publisher: World Scientific
ISBN: 9814497673
Category : Science
Languages : en
Pages : 245
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Book Description
The porphyrins, chlorophylls, bilins and related tetrapyrroles are vital for all living organisms. Natural and synthetic tetrapyrroles are used extensively in foods, cosmetics, biotechnology, pharmaceuticals, diagnostics and medicine. Methods for their separation and characterization therefore, have a very wide area of applications. Yet, there is a dearth of books dedicated to HPLC and HPLC/MS of tetrapyrroles. Lim addresses this problem admirably by providing practical HPLC and HPLC/MS protocols coupled with in-depth chromatographic and mass spectrometric reference data. These are invaluable in the analysis, identification and characterization of porphyrins, chlorophylls, bilins and other related compounds found in biological and clinical materials. HPLC method development and optimization for coupling to mass spectrometry are also described in rich detail. Sample preparation, and suggestions for avoiding procedural artifacts during extraction of clinical and biological samples are discussed. Clinical biochemists involved in biochemical diagnosis of human porphyrias will find this monograph assuredly helpful, as would analysts, biochemists and chemists involved in the separation, isolation and characterization of natural and synthetic tetrapyrroles. Undoubtedly, Lim has contributed a master-piece containing sufficient background material for beginners and up-to-date references for all researchers in the field.
