Gas Chromatography Using Simultaneously Programmed Temperature and a Programmed Longitudinal Negative Temperature Gradient PDF Download
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Author: M. Coudert
Publisher:
ISBN:
Category :
Languages : en
Pages : 14
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Book Description
Author: M. Coudert
Publisher:
ISBN:
Category :
Languages : en
Pages : 14
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Book Description
Author:
Publisher:
ISBN:
Category : Gas chromatography
Languages : en
Pages : 856
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Book Description
Author: Austin V. Signeur
Publisher: Springer
ISBN:
Category : Reference
Languages : en
Pages : 1390
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Book Description
The bibliography which follows represents an effort to provide the active or potential worker in the field of gas chromatography with references to the theory, methodology, and applications of this phase of chemistry. A review of the cited references will afford background for proposed applications, suggest possible solution of a problem, furnish an acquaintance with trends and current work being conducted, and furnish a realization of the possibilities and po tentialities of a technique for the separation, identification, and more recently-preparation of materials. To augment the numerous literature references, titles of papers presented at various scientific meetings are given. Some of these papers have not been published, but they represent a part of the literature of this technique since they indicate the progress and thinking of workers in this field, and provide the opportunity for those with mutual interests to communicate with each other for further details. To afford ready referral for additional information, references are given, when available, to Chemical Abstracts, orto the abstract in the program of the meeting. To accommodate those who may desire microfilm or photostatic copies of the published works, complete pagination is given rather than initial page references. Austin V. Signeur CONTENTS Listing of Bibliographie Entries (Alphabetized according to first author) . . . . . . . . . . . 1 Author Index. . . . . . . . . . . . . . . . . . . . . • . . . . 279 . • . . . .
Author: Walter Edgar Harris
Publisher: New York : J. Wiley
ISBN:
Category : Gas chromatography
Languages : en
Pages : 334
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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: 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: Vivek Jain
Publisher:
ISBN:
Category :
Languages : en
Pages : 310
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Book Description
Author: Jesse Alberto Contreras
Publisher:
ISBN:
Category : Gas chromatography
Languages : en
Pages : 274
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Book Description
Author: Paul John McLaughlin
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
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.
