Programmable Selectivity and Fast Temperature Programming for High-speed GC Analysis of Wide Boiling-point-range Mixtures PDF Download

Author: Carrie Ann Leonard Coutant
Publisher:
ISBN:
Category :
Languages : en
Pages : 366

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Author: Heather Lynne Smith
Publisher:
ISBN:
Category :
Languages : en
Pages : 324

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Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 832

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Author: Andrew James Grall
Publisher:
ISBN:
Category :
Languages : en
Pages : 312

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Author: Daniel Bahaghighat
Publisher:
ISBN:
Category :
Languages : en
Pages : 155

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A combination of four instrumental systems and one chemometric method are presented that improves the efficiency, resolving power (i.e. peak capacity/ peak capacity production), and lessens the typical time of multi-dimensional gas chromatography (MDGC) separation in a straightforward, easily interpretable manner. Application of partial modulation via a commercially available high speed pulse flow valve for two-dimensional gas chromatography (GC×GC) is shown to provide ultra-fast modulation with modulation periods (P[subscript]M) as short as 50 ms. This technique performs a combination of vacancy chromatography and frontal analysis by an injection of carrier gas at the union of the first column (1D) and second column (2D). Each pulse disturbance in the analyte concentration profile as it exits the first column (1D) results in vacancy like data that is readily converted into a second separation (2D). A three-step process converts the raw data into a format equivalent to a traditional GC×GC separation chromatogram: 1. signal differentiation, 2. inversion of data, 3. baseline correction. The first instrumental system (GC×GC-Flame Ionization Detector (FID) with a P[subscript]M of 500 ms, separating a 115-component mixture composed of a wide range of boiling points (36–372 °C) compounds with apparent peak widths on the 2D, 2W[subscript]b, ranged from 10 to 40 ms, producing a 2D peak capacity, 2n[subsciprt]c, of ~ 20, and the total peak capacity, n[subscript]c,2[subscript]D, was 7200 or a peak capacity production of 1200 peaks/min. For a P[subscript]M of 75 ms, separating a low boiling point 15-component mixture isothermally, apparent peak widths on the 2D, 2W[subscript]b, averaged 10 ms producing a 2D peak capacity, 2n[subscript]c, of ~ 7.5, with a peak capacity production of 950 peaks/min. The second system incorporated a high temperature diaphragm valve modulator and a pulse valve flow modulator to create a three-dimensional gas chromatography system (GC3) with a peak capacity production of 1000 peaks/min which is a ~5 times increase in efficiency compared to other GC3 systems. The third instrumental design established capability with a time-of-flight mass spectrometer (TOF), a method was developed for GC×GC-TOF separation in which a concentration study was conducted with an 18-component mixture and a P[subscript]M of 50 ms. The subsequent data was deconvoluted with multivariate curve resolution-alternating least squares (MCR-ALS) in order to obtain their identification via match values. The resulting MCR-ALS data was converted in a similar manner as before into GC×GC chromatograms. Lastly, the pulse valve flow modulator was demonstrated to conduct continuous gas sampling of a system via one dimensional (1D) chromatography. The method applies the partial modulation technique to create frontal analysis peaks that are then transformed into a 1D chromatogram of analytes from a dynamic system that present a novel method of continuous sampling.

Author: Carl A. Burtis
Publisher: Elsevier Health Sciences
ISBN: 0323292062
Category : Medical
Languages : en
Pages : 1102

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A condensed, easier-to-understand student version of the acclaimed Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, Tietz Fundamentals of Clinical Chemistry and Molecular Diagnostics, 7th Edition uses a laboratory perspective in providing the clinical chemistry fundamentals you need to work in a real-world, clinical lab. Coverage ranges from laboratory principles to analytical techniques and instrumentation, analytes, pathophysiology, and more. New content keeps you current with the latest developments in molecular diagnostics. From highly respected clinical chemistry experts Carl Burtis and David Bruns, this textbook shows how to select and perform diagnostic lab tests, and accurately evaluate results. Authoritative, respected author team consists of two well-known experts in the clinical chemistry world. Coverage of analytical techniques and instrumentation includes optical techniques, electrochemistry, electrophoresis, chromatography, mass spectrometry, enzymology, immunochemical techniques, microchips, automation, and point of care testing. Learning objectives begin each chapter, providing measurable outcomes to achieve after completing the material. Key words are listed and defined at the beginning of each chapter, and bolded in the text. A glossary at the end of the book makes it quick and easy to look up definitions of key terms. More than 500 illustrations plus easy-to-read tables help you understand and remember key concepts. New chapters on molecular diagnostics include the principles of molecular biology, nucleic acid techniques and applications, and genomes and nucleic acid alterations, reflecting the changes in this rapidly evolving field. New content on clinical evaluation of methods, kidney function tests, and diabetes is added to this edition. NEW multiple-choice review questions at the end of each chapter allow you to measure your comprehension of the material. NEW case studies on the Evolve companion website use real-life scenarios to reinforce concepts.

Author: Matthew S. Klee
Publisher: Hewlett-Packard, Avondale Division
ISBN: 9781880313008
Category : Gas chromatography
Languages : en
Pages : 132

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Author: Leonid M. Blumberg
Publisher: John Wiley & Sons
ISBN: 3527632263
Category : Science
Languages : en
Pages : 363

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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:
Publisher:
ISBN:
Category : Dissertation abstracts
Languages : en
Pages : 816

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Experimental data are presented for the first time in support of a theoretical model of band broadening proposed by Blumberg (1997). This model addresses the effects of the compressibility of the mobile phase in gas chromatography and presents an equation derived from only two mutually independent variables. Solutions of decane and tridecane in hexane were analyzed at pressures ranging from 15 to 150 psi. Six different columns were used that varied in length, internal diameter and film thickness. Theoretical plate heights were obtained from this data and plotted versus the average linear carrier gas velocity (Golay type plots). These plots showed that at high pressures the Blumberg model fit the experimental data statistically significantly better than the earlier model proposed by Golay. The Blumberg model also accurately predicts the relationship between the optimum linear carrier gas velocity and the temperature. The second part of this work explores the scope and limitations of fast temperature programming in the fast GC analyses of various sample types. These samples included polycyclic aromatic hydrocarbons (PAHs), hydrocarbons and food samples. Programming rates of up to 1200 degrees C/min were used. These fast programming rates were obtained by using "flash" temperature programming, controlled by resistive heating of a metal tube that enclosed a capillary column. The precision of peak data was found to be good, less than 5% for peak areas and 4% for retention times. However, a slight, but statistically significant decrease in peak areas was seen above programming rates of 240 degrees C/min. Microwave assisted extraction (MAE) was used to extract 2,6-di-(tert-butyl)-4-methylphenol, BHT, from chewing gum and breakfast cereal. The extraction was followed by a fast GC analysis (less than 4 minutes) using "flash"O ̂temperature programming. MAE reduced the sample preparation time, from hours to minutes, and consequently reduced, the total analysis time. Extraction times longer than 5 minutes gave decreased recoveries of BHT.