Analytical Gas Chromatography

About this book

Gas chromatography remains the world's most widely used analytical technique, yet the expertise of a large proportion of chromatographers lies in other fields. Many users have little real knowledge of the variablesin the chromatographic process, the interaction between those variables, how they are best controlled, how the quality of their analytical results could be improved, and how analysis times can be shortened to facilitate the generation of a greater numberof more reliable results on the same equipment. An analyst with a more comprehensive understanding of chromatographic principles and practice, however, can often improve the quality of the data generated, reduce the analytical time, and forestall the needto purchase an additional chromatograph or another mass spectrometer.The Second Edition of "Analytical Gas Chromatography" is extensively revised with selected areas expanded and many new explanations and figures. The section on sample injection has been updated to include newer concepts of split, splitless, hot and cold on-column, programmed temperature vaporization, and large volume injections.Coverage of stationary phases now includes discussion, applications, and rationale of the increased thermal and oxidative resistance of the newly designed silarylenepolysiloxane polymers. Conventional and "extended range" polyethylene glycol stationary phases are examined from the viewpoints of temperature range and retention index reliabilities, and the chapter on "Variables" has been completely rewritten. The ways in which carrier gas velocity influences chromatographic performance is considered in detail, and includes what may be the first rational explanation of the seemingly anomalous effects that temperature exercises on gas viscosity (and gas flow).The practical effects that these changes cause to the chromatography is examined in pressure, flow, and "EPC" regulated systems. "Column Selection, Installation, and Use" has been completely rewritten as well. The accuracy of theVan Deemter plots has been greatly enhanced; a new program corrects for the first time for the changes in gas density and diffusion that occur during the chromatographic process because of solute progression through the pressure drop of the column. A new section has also been added on meeting thespecial requirements of columns destined for mass spectral analysis. The chapter on "Special Applications" has been expanded to include considerations of "selectivity tuning," of fast analysis, and the section of Applications has been thoroughly updated and expanded.This book incorporates nearly 60 per cent new material. It covers the newest concepts and materials for sample injection and stationary phases. It presents detailed consideration of the influence of carrier gas velocity on practical aspects of chromatographic performance. It contains a chapter on "Special Analytical Techniques" which includes consideration of selectivity tuning and fast analysis. It provides a new section addressing the special requirements of columns to be used in mass spectral analysis. It includes an improved program that greatly enhances the accuracy of the Van Deemter plots by more accurately depicting localized chromatographic conditions at each point in the column.

Contents

Preface. Introduction: General Considerations. A Simplistic Approach. A Simplistic Approach. Simplistic Comparisons of Packed and Open Tubular Columns. A Simplified Theory of the Chromatographic Process. Separation of Components. Effect of Carrier Gas Velocity. References. The Open Tubular Column: General Considerations. The Tubing. Sources of Activity. Structural Flaws. Flexible Columns of Conventional Glasses. Silanol Deactivation. Column Coating. References. Sample Injection: General Considerations. Extra-Chromatographic Phenomena Influencing Band Length. Chromatographic Phenomena Influencing Band Length. Hot Vaporizing Injection Methods. Programmed Temperature Vaporizing Injector (PTV). On-Column Injection. Large Volume Injection. Purge and Trap Sampling. Selecting the Proper Injection Mode. References. The Stationary Phase: General Consideration. Stationary Phase Polarity and Selectivity. Polysiloxane Stationary Phases. Aryl Substituted Siloxanes.Bonded, Crosslinked, and/or Immobilized Stationary Phases. Polyethylene Glycol Stationary Phases. Enantiomer Separations. Other Special-Selectivity Stationary Phases. Gas-Solid Absorption Columns. References. Variables in the Gas Chromatographic Process: General Considerations. Volumetric Column Flow. Carrier Gas Viscosity. Comparing Calculated to Experimental Volumetric Flows. Volumetric Column Flow & Average Linear Velocity. Regulation of Gas Flow and Gas Velocity. Average Linear Velocity & Chromatographic Efficiency. Calculating Reliable Estimates A, B, and C. Theory & Practice. Choice of Carrier Gas. The Effect of Solute Retention Factors. The Effect of Column Length. The Effect of Column I.D. The Effect of Stationary Phase Film Thickness. The Effect of Stationary Phase Diffusivity. The Effects of Temperature. Optimum Practical Gas Velocity. Temperature Programmed Considerations. Column Flow Under Temperature Programmed Conditions. Average Linear Velocity Under Temperature Programmed Conditions.D<-/B> and D<-/B> under Temperature Programmed Considerations. Solute Retention Under Temperature Programmed Considerations. Chromatographic Efficiency Under Temperature Programmed Conditions. Changes in Solute Elution Order. References. Column Selection, Installation, and Use: General Considerations. Selecting the Stationary Phase. Stationary Phase Selectivity. Selecting the Column Diameter. Selecting the Column Length. Selecting the Stationary Phase Film Thickness. Column Installation. Column Condition. Optimizing Operational Parameters for Specific Column. Columns for Mass Spectrometry. References. Instrument Conversion and Adaptation: General Considerations. Oven Considerations. Carrier Gas Considerations. Packed to Large Diameter-Diameter Open Tubular Conversion. Packed to Capillary Conversion. Make-Up Gas Considerations. Inlet Deactivation. References. Special Analytical Techniques: General Consideration. Flow Stream Switching. Multidimensional Chromatography. Recycle Chromatography. Specifically Designed Stationary Phases. Selectivity Tuning. Vapor Samples and Headspace Injections. Fast Analysis. References. Selected Applications: General Considerations. Food, Flavor, and Fragrance Applications. Petroleum-and Chemical-Related Applications. Environmental Applications. Biological and Medical Applications. References. Troubleshooting: General Considerations. Use of Test Mixtures. Column Bleed. Temperature and Oxygen Effects. Column Rejuvenation. Peak Distortion. Other Sorptive Residues. Colum Coupling and Junction Problems. Flame Jet Problems. Miscellaneous Chromatographic Problems. References. Appendix I. Abbreviations, Terms, and Nomenclature. Subject Index.

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