Microchip Thermal Gradient Gas Chromatography PDF Download
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Author: Anzi Wang
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 143
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Book Description
Although the airbath oven is a reliable heating method for gas chromatography (GC), resistive heating is needed for higher analytical throughput and on-site chemical analysis because of size, heating rate and power requirements. In the last thirty years, a variety of resistive heating methods were developed and implemented for both benchtop and portable GC systems. Although fast heating rates and low power consumption have been achieved, losses in column efficiency and resolution, complex construction processes and difficulties experienced in recovering damaged columns have also become problematic for routine use of resistively heated columns. To solve these problems, a new resistively heated column technique, which uses metal columns and self-insulated heating wires, was developed for capillary gas chromatography. With this method, the total thermal mass was significantly less than in commercial column assemblies. Temperature-programming using resistive heating was at least 10 times faster than with a conventional oven, while only consuming 1−5% of the power that an oven would use. Cooling a column from 350 °C to 25 °C with an air fan only required 1.5 min. Losses in column efficiency and peak capacity were negligible when compared to oven heating. The major trade-off was slightly worse run-to-run retention time deviations, which were still acceptable for most GC analyses. The resistively heated column bundle is highly suitable for fast GC separations and portable GC instruments.
Author: Anzi Wang
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 143
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Book Description
Although the airbath oven is a reliable heating method for gas chromatography (GC), resistive heating is needed for higher analytical throughput and on-site chemical analysis because of size, heating rate and power requirements. In the last thirty years, a variety of resistive heating methods were developed and implemented for both benchtop and portable GC systems. Although fast heating rates and low power consumption have been achieved, losses in column efficiency and resolution, complex construction processes and difficulties experienced in recovering damaged columns have also become problematic for routine use of resistively heated columns. To solve these problems, a new resistively heated column technique, which uses metal columns and self-insulated heating wires, was developed for capillary gas chromatography. With this method, the total thermal mass was significantly less than in commercial column assemblies. Temperature-programming using resistive heating was at least 10 times faster than with a conventional oven, while only consuming 1−5% of the power that an oven would use. Cooling a column from 350 °C to 25 °C with an air fan only required 1.5 min. Losses in column efficiency and peak capacity were negligible when compared to oven heating. The major trade-off was slightly worse run-to-run retention time deviations, which were still acceptable for most GC analyses. The resistively heated column bundle is highly suitable for fast GC separations and portable GC instruments.
Author: Carlos R. Vilorio
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
There has been substantial market demand for a portable Gas Chromatography (GC) system. Throughout the years, much progress has been made on fabricating a micro system that works as well as a benchtop system. Unfortunately, even though many substrates, channel types, channel widths, temperature control systems, and interface solutions have been attempted, existing versions of the micro-GC still fall short of the ideal. This thesis presents the design, fabrication, and testing of a silicon based micro-GC column that presents a solution for interfacing and heating of the chip. A polyimide resin is used to create a durable high temperature low thermal mass interface with the chip, while a silk screen method is demonstrated for easy printing of heaters. Chromatogram results are shown in both Temperature Program and Thermal Gradient runs.
Author: Colin Poole
Publisher: Elsevier
ISBN: 0128206772
Category : Science
Languages : en
Pages : 938
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Book Description
Gas Chromatography, Second Edition, offers a single source of authoritative information on all aspects relating to the practice of gas chromatography. A focus on short, topic-focused chapters facilitates the identification of information that will be of immediate interest for familiar or emerging uses of gas chromatography. The book gives those working in both academia and industry the opportunity to learn, refresh and deepen their understanding of fundamental and instrumental aspects of gas chromatography and tools for the interpretation and management of chromatographic data. Users will find a consolidated guide to the selection of separation conditions and the use of auxiliary techniques. This new edition restores the contemporary character of the book with respect to those involved in advancing the technology, analyzing the data produced, or applying the technique to new application areas. New topics covered include hyphenated spectroscopic detectors, micromachined instrument platforms, derivatization and related microchemical techniques, petrochemical applications, volatile compounds in the atmosphere, and more. - Includes chapters written by recognized authoritative and visionary experts in the field, thus providing an overview and focused treatments on a single topic - Provides comprehensive coverage of modern gas chromatography, from theory, to methods and selected applications - Places modern developments in research literature into a general context not always apparent to inexperienced users of the techniques
Author: Leonid M. Blumberg
Publisher: John Wiley & Sons
ISBN: 3527632263
Category : Science
Languages : en
Pages : 363
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Book Description
This book provides a comprehensive up-to-date overview of temperature-programmed gas chromatography (GC). The first part of the book introduces the reader to the basics concepts of GC, as well as the key properties of GC columns. The second part describes the mathematical and physical background of GC. In the third part, different aspects in the formation of a chromatogram are discussed, including retention times, peak spacing and peak widths. An invaluable reference for any chromatographer and analytical chemist, it provides all the answers to questions like: At what temperature does a solute elute in a temperature-programmed analysis? What is the value of the retention factor of eluting solute? How wide are the peaks? How large is the time distance between two peaks? How do all these parameters depend on the heating rate?
Author: Austin Richard Foster
Publisher:
ISBN:
Category :
Languages : en
Pages : 159
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Book Description
Author: Marie Thes M. Castro
Publisher:
ISBN:
Category :
Languages : en
Pages : 218
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Book Description
Author: Samuel Avila
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Gas chromatography (GC) is an analytical chemistry tool used to determine the chemical composition of a gas sample by separating sample analytes as they travel through a GC column. Recent efforts have been made to understand and control gas chromatography separations with a negative thermal gradient on the column. The present work presents results from thermal gradient GC separations on two GC columns in different configurations (serpentine and radial) in a stainless-steel plate. Methods to fabricate the GC systems capable of isothermal, temperature programmed and thermal gradient separations are presented. Isothermal experimental data from the serpentine column were used to fit retention and dispersion parameters in a transport model that simulates GC separation for hydrocarbons C12-C14. Transport model simulated retention times and peak widths matched experimental values well for isothermal, temperature programmed and thermal gradient separations. The validated transport model was used to study the effect of static (not varying temporally) thermal gradients on GC separations with varying injection widths, injection band shapes and stationary phase thickness. Resolution results from different heating conditions were considered comparable if retention times for each analyte were within 5%. An optimal, static thermal gradient is shown to reduce analyte band spreading from axially-varying velocity gradients with resolution improvements over isothermal separations of up to 8% for analytes with similar retention factors. Static thermal gradients have a larger effect on fronting peak shape than tailing peak shape. Stationary phase distribution acts similar to a velocity gradient and can be corrected by a thermal gradient. Another transport model was created from isothermal experimental data on a commercial column for hydrocarbons C12-C20. An optimal, static thermal gradient does not improve resolution for all analyte pairs. An optimal, dynamic (varying tempo-rally) thermal gradient is created by uniformly increasing the temperature on an optimal, static thermal gradient. Improvements in resolution of up to 20% are achievable over temperature programmed GC separation. A dynamic thermal gradient can also correct for a poor sample injection by creating a temperature trap at the beginning of the column.
Author: Jesse Alberto Contreras
Publisher:
ISBN:
Category : Gas chromatography
Languages : en
Pages : 274
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Book Description
Author: Walter Edgar Harris
Publisher: New York : J. Wiley
ISBN:
Category : Gas chromatography
Languages : en
Pages : 334
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Book Description
Author: M. Coudert
Publisher:
ISBN:
Category :
Languages : en
Pages : 14
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Book Description
