Principles of gas chromatography

The general principles of chromatography have been discussed in Chapter 2. However, a more detailed account in the context of GC is presented herein the reader is also referred to the Glossary for additional detail and explanations of the terminology used. The treatment of theoretical aspects is at a level which should enable the analyst to obtain maximum efficiency and performance from the system and application. 

There are broadly three modes in which GC is carried out  

gas-liquid chromatography (GLC) using a packed column with the liquid stationary phase coated onto inert support particles  

capillary column GC where open tubular columns are used with the liquid or solid stationary phase coated onto the inner walls of the column tubing referred to as wall coated, porous layer and surface coated open tubular columns (WCOT, PLOT and SCOT) and 

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The principle of gas chromatography (GC) is similar to that of liquid chromatography or TLC, in that compounds in mixtures are separated from each other based on their affinity for a resin. GC is performed on volatile... 

A standard arrangement for sampling gaseous products downstream of the reactor is shown in Fig. 5. In a needle valve (or a similar device), the reactor effluent is depressurized and the flow rate is controlled. In the vast majority of cases, the analytical instrument of the choice will be a gas chromatograph equipped with a capillary column, because such an instrument often allows a good separation of the products and, if equipped with an appropriate detector, a reliable quantitative analysis of these products. The working principle of gas chromatography, however, is inherently... 

Describe the principles of gas chromatography-mass spectrometry. What are its benefits ... 

Many methods depend on the separation of a fluid mixture. Among these, gas chromatography (GC) stands out [8]. Suitable devices for on-line control were developed from laboratory gas chromatographs and operate very rehably. However, they can be expensive because of the associated program controls. The principle of gas chromatography is that a carrier gas (helium) is passed over a tubular column of a fine solid. A sample is injected into the carrier gas stream and the gas... 

Adsorption Chromatography. The principle of gas-sohd or Hquid-sohd chromatography may be easily understood from equation 35. In a linear multicomponent system (several sorbates at low concentration in an inert carrier) the wave velocity for each component depends on its adsorption equihbrium constant. Thus, if a pulse of the mixed sorbate is injected at the column inlet, the different species separate into bands which travel through the column at their characteristic velocities, and at the oudet of the column a sequence of peaks corresponding to the different species is detected. 

H.H.Strain, AnalChem 30, 620-29 (1958) (Chromatographic analysis by differential migration) 66)R.L.P ecsok,Edit, "Principles and Practice of Gas Chromatography ,... 

The first reported use of a vapor as the mobile phase is attributed to Martin and Synge in 1941. They used the principles of partition chromatography, whereas James and Martin, in 1952, described the first application of this method, gas-liquid chromatography (GLC), for the analysis of fatty acids and amines. Gas adsorption chromatography (GSC), on the other hand, involves the use of a solid stationary phase and separation is based on an adsorptive mechanism. This technique was first described in 1947 in a doctoral thesis by Prior,under the supervision of Professor Cremer, and subsequently in their 1951 publication.f ... 

Precision and accuracy Gas chromatography enables analysts to perform quantitative analysis accurately imder a variety of conditions. Automation and computer control of all critical chromatographic parameters has produced levels of precision and accuracy not thought possible a decade ago. There are many excellent pubhcations detailing the theory and practice of gas chromatography [8-14]. This chapter is trying to highhght some of more important principles of GC and to discuss some apphcations to food separation and analysis. 

The principle of adsorption chromatography is the same as for gas chromatography, which was discussed in some detail in a previous section. Another description is not very essential at this point. The most popular filling or packing for... 

The present Chapter includes a description of the general methods and basic principles of gas-liquid chromatography. The development of the method as applied to various classes of carbohydrate derivatives is surveyed, and this treatment is followed by a discussion of mobilities of compounds in relation to their structure. Applications of the method to specific problems are described, and the liquid phases used in gas-liquid chromatography of carbohydrate derivatives are summarized. Finally, an attempt is made to assess the relative merits of gas-liquid chromatography and other chromatographic methods as applied to carbohydrate derivatives. 

The preceding discussion was provided to give a basic understanding of the principles of gas-liquid chromatography and of the various factors that contribute to the separations achieved on packed columns. Much of the discussion was drawn from a number of textbooks or monographs, to... 

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