Chromatography can be divided into three basic types that include gas, liquid, and supercritical fluid chromatography. Liquid chromatography can further be divided into ion exchange, separations based on size, and even extended to gel-based electrophoretic techniques. This book will provide a basic introduction to Basic Gas Chromatography, co - authored by McNair and Bonelli and published by Varian Instruments. Some material is also drawn from the earlier Wiley book by Miller, Chromatography: Concepts and Contrasts. We have attempted to write a brief, basic, introduction to GC following the objectives for titles in this series. Gas chromatography 4 is the process of taking a sample and injecting it into the instrument, turning the 5 solvent and analytes into gaseous form, and separating the mixture of 6 compounds into individual peaks (and preferably individual compounds). INTRODUCTION Gas chromatography is one of the most widely used techniques for analyzing hydrocarbon mixtures. Some of the advantages of chromatography are the range of measurement (from ppm levels up to 100%), the detection of a wide range of components, and the repeatability of the measurements. Some terminologies in chromatography Retention time (tR) -Is the time taken between the point of injection and the peak maximum recorded on the chromatogram -The total time that a compound spends in both the mobile phase and stationary phase - is the time taken for the analyte to pass through the column -It is generally reported in minutes INTRODUCTION:- Gas chromatography -"It is a process of separating component(s) from the given crude drug by using a gaseous mobile phase." It involves a sample being vaporized and injected onto the head of the chromatographic column. The sample is transported through the column by the flow of inert, gaseous mobile phase. The This introduction presents an overview of key concepts covered in the subsequent chapters of this book. The book focuses on capillary gas chromatography (GC). It describes the basic principles and equations in chromatography followed by an overview of instrumentation. GC is the premier technique for separation and analysis of volatile compounds. Introduction: Gas chromatography (GC) is an analytical technique used to separate the chemical components of a sample mixture and then detect them to determine their presence or absence and/or how much is present. These chemical components are usually organic molecules or gases. For GC to be successful in their analysis, these components need 1 Introduction, 1 1.1 Liquid versus Gas Chromatography, 2 1.2 Modern versus Traditional LC Procedures, 3 1.3 How Did Modem LC Arise?, 8 1.4 The Literature of LC, 9 1.5 About the Book, 12 References, 13 Bibliography, 13 2 Basic Concepts and Control of Separation, 15 2.1 The Chromatographic Process, 16 2.2 Retention in LC, 22 1 Introduction to Capillary Gas Chromatography 11344vch01.indd 6344vch01.indd 6 004.05.2007 16:05:224.05.2007 16:05:22. 7 peak identities or overlapping problems, but there are cases where complete separation is not possible. Each peak in the chromatogram is assigned a retention time. It is the time re- Gas Chromatography In GC, the sample is vaporized and injected onto the head of a chromatographic column. Elution is brought about by the flow of an inert gaseousmobile phase, the mobile phase does not interact with molecules of the analyte (i.e.,