Author: Ashur Rael Publisher: ISBN: Category : Languages : en Pages : 262
Book Description
In the area of forensic chemistry, improved or new analysis methods are continually being investigated. One common and powerful technique used in forensic chemistry is wall-coated open-tubular column (WCOT) gas chromatography with electron ionization single quadrupole mass spectrometry (GC-MS). Improvements to and effectiveness of alternatives to this instrumental platform were explored in an array of parallel inquiries. The areas studied included the column for the chromatographic separation, the universal detection method employed, and the fragmentation method used to enhance molecular identification. Superfine-micropacked capillary (SFμPC) columns may provide an alternative to commercial packed GC columns and WCOT GC columns that combines the benefits of the larger sample capacity of packed columns and the benefits of the excellent separation capabilities and mass spectrometry (MS) flow rate compatibility of WCOT columns. SFμPC columns suffer from high inlet pressure requirements and prior reported work has required specialized instrumentation for their use. Fabrication of and chromatography with SFμPC GC columns was successfully achieved with typical GC-MS instrumentation and within the flow rate limit of a MS. Additionally, the use of higher viscosity carrier gasses was demonstrated to reduce the required inlet pressure for SFμPC GC columns. Recently, a new vacuum ultraviolet spectrometer (VUV) universal detector has been commercialized for GC. The ability of VUV detectors to acquire absorbance spectra from 125 nm to 430 nm poses a potential alternative to MS. As such, GC-VUV provides an exciting potential alternative approach to achieving excellent quantitative and qualitative analysis across a wide range of analytes. The performance of VUV and MS detectors for forensic analysis in terms of quantitative and qualitative analysis was compared. Analysis of alkylbenzenes in ignitable liquids was explored, which can be important evidence from suspected arson fires and are difficult to differentiate with MS. The VUV detector was found to have superior specificity and comparable sensitivity to the MS detector in scan mode. Addition of thermolysis (Th) as an orthogonal fragmentation pathway provides the opportunity to increase the differences between MS fragmentation patterns. Fragmentation has been widely established to aid in identification of molecules with MS by providing characteristic fragments at characteristic relative abundances. However, molecules with very similar structures do not result in sizable spectral differences in all cases with typical MS fragmentation techniques. A series of Th units were fabricated and integrated into GC-Th-MS instruments. Th-MS was conducted with the thermally labile nitrate esters across a range of instrumentation and thermal conditions.
Author: Zackery Ray Roberson Publisher: ISBN: Category : Languages : en Pages : 200
Book Description
In forensic chemistry, a quicker and more accurate analysis of a sample is always being pursued. Speedy analyses allow the analyst to provide quick turn-around times and potentially decrease back-logs that are known to be a problem in the field. Accurate analyses are paramount with the futures and lives of the accused potentially on the line. One of the most common methods of analysis in forensic chemistry laboratories is gas chromatography, chosen for the relative speed and efficiency afforded by this method. Two major routes were attempted to further improve on gas chromatography applications in forensic chemistry. The first route was to decrease separation times for analysis of ignitable liquid residues by using micro-bore wall coated open-tubular columns. Micro-bore columns are much shorter and have higher separation efficiencies than the standard columns used in forensic chemistry, allowing for faster analysis times while maintaining the expected peak separation. Typical separation times for fire debris samples are between thirty minutes and one hour, the micro-bore columns were able to achieve equivalent performance in three minutes. The reduction in analysis time was demonstrated by analysis of ignitable liquid residues from simulated fire debris exemplars. The second route looked at a relatively new detector for gas chromatography known as a vacuum ultraviolet (VUV) spectrophotometer. The VUV detector uses traditional UV and far-ultraviolet light to probe the pi and sigma bonds of the gas phase analytes as well as Rydberg traditions to produce spectra that are nearly unique to a compound. Thus far, the only spectra that were not discernable were from enantiomers, otherwise even diastereomers have been differentiated. The specificity attained with the VUV detector has achieved differentiation of compounds that mass spectrometry, the most common detection method for chromatography in forensic chemistry labs, has difficulty distinguishing. This specificity has been demonstrated herein by analyzing various classes of drugs of abuse and applicability to "real world" samples has been demonstrated by analysis of de-identified seized samples
Author: Xinghua Guo Publisher: BoD – Books on Demand ISBN: 9535112279 Category : Science Languages : en Pages : 226
Book Description
For decades gas chromatography has been and will remain an irreplaceable analytical technique in many research areas for both quantitative analysis and qualitative characterization/identification, which is still supplementary with HPLC. This book highlights a few areas where significant advances have been reported recently and/or a revisit of basic concepts is deserved. It provides an overview of instrumental developments, frontline and modern research as well as practical industrial applications. The topics include GC-based metabolomics in biomedical, plant and microbial research, natural products as well as characterization of aging of synthetic materials and industrial monitoring, which are contributions of several experts from different disciplines. It also contains best hand-on practices of sample preparation (derivatization) and data processing in daily research. This book is recommended to both basic and experienced researchers in gas chromatography.
Author: Publisher: Newnes ISBN: 0444626247 Category : Science Languages : en Pages : 525
Book Description
Gas chromatography mass spectrometry (GC-MS) has been the technique of choice of analytical scientists for many years. The latest developments in instrumentation, including tandem mass spectrometry (MS-MS) and time-of-flight (TOF) detectors, have opened up and broadened the scope of environmental analytical chemistry. This book summarizes the major advances and relevant applications of GC-MS techniques over the last 10 years, with chapters by leading authors in the field of environmental chemistry. The authors are drawn from academia, industry and government. The book is organized in three main parts. Part I covers applications of basic GC-MS to solve environmental-related problems. Part II focuses on GC-MS-MS instrumentation for the analyses of a broad range of analysis in environmental samples (pesticides, persistent organic pollutants, endocrine disruptors, etc.). Part III covers the use of more advanced GC-MS techniques using low- and high-resolution mass spectrometry for many applications related to the environment, food and industry. Summarizes the major advances of GC-MS techniques in the last decade Presents relevant applications of GC-MS techniques Covers academic, industrial and governmental sectors
Author: O. David Sparkman Publisher: Academic Press ISBN: 0080920152 Category : Science Languages : en Pages : 633
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
Author: Chih-Hao Wang Publisher: ISBN: Category : Languages : en Pages : 47
Book Description
Disinfection by-products (DBPs) are a significant concern in drinking water quality. Haloacetic acids, which are generated from disinfection processes, are one of the major groups in disinfection by-products. Because they induce potential harmful effects for human health, the US government has already established regulations to control the levels of haloacetic acids in drinking water. In order to control the presence of haloacetic acids in drinking water and monitor other potential harmful compounds, an appropriate analytical method is needed. In this study, a gas chromatography (GC) method was developed for detecting haloacetic acids in water. Three different derivatization reagents were compared for sensitivity enhancement in conjunction with mass spectrometry (MS) and vacuum ultraviolet (VUV) detection. A model study was first performed using acetic acid and then the study was extended to haloacetic acids. The sensitivity of GC-MS and GCVUV had been increased after the derivatization. However, it also had many shortcomings and challenges that needed to be overcome: (1) the efficiency of derivatization was low; (2) the benzyl alcohol derivatization caused many side reactions in complex samples and generated high intensities of interference noises. Further study will need to modify the GC-MS and GCVUV methods, especially for the detection of brominated trihaloacetic acids.
Author: Diane C Turner Publisher: Royal Society of Chemistry ISBN: 1782629289 Category : Science Languages : en Pages : 340
Book Description
Gas chromatography–mass spectrometry (GC-MS) is a powerful way to analyse a range of substances. It is used in everything from food safety to medicine. It has even been used to protect endangered vultures through analysis of poisonous pesticide molecules in their environment! I want to apply this technique, where do I begin? Is GC-MS is the right technique to use? How do I prepare my samples and calibrate the instruments? This textbook has the answers to all these questions and more. Throughout the book, case studies illustrate the practical process, the techniques used and any common challenges. Newcomers can easily search for answers to their question and find clear advice with coloured images on how to get started and all subsequent steps involved in using GC-MS as part of a research process. Readers will find information on collecting and preparing samples, designing and validating methods, analysing results, and troubleshooting. Examples of pollutant, food, oil and fragrance analysis bring the theory to life. The authors use their extensive experience teaching GC-MS theory and practice and draw on their combined backgrounds applying the technique in academic and industry settings to bring this practical reference together. The authors also design and teach the Royal Society of Chemistry’s Pan Africa Chemistry Network GC-MS course, which is supported by GSK.
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: Wilfried M.A. Niessen Publisher: CRC Press ISBN: 9781420029512 Category : Science Languages : en Pages : 530
Book Description
This volume details the principles and instrumentation of gas chromatography-mass spectrometry (CG-MS), and outlines industrial, environmental, pharmaceutical, clinical, toxicological, forensic and food-related applications, revealing findings from the laboratories of 40 contributing scientists around the world using GC-MS in practice. It describes upstream and downstream applications of GC-MS in the petroleum industry and identifies chlorinated compounds in the environment with quadrupole ion-trap technology and high-resolution sector instruments.
Author: Ashur Rael
Author: Zackery Ray Roberson
Author: Xinghua Guo
Author: 
Author: O. David Sparkman
Author: Chih-Hao Wang
Author: Diane C Turner
Author: Ralf Zimmermann
Author: Wilfried M.A. Niessen
Author: J. F. J. Todd