Chromatographic principles

Smith (Editor), Chromatographic and Electrophoretic Techniques, Vols. I and II, 

Snyder, Principles of Adsorption Chromatography, Marcel Dekker, New York, 1968. 

Otocka, Modem gel permeation chromatography,Accounts Chem. Res., 6(1973) 348. 

High-pressure ion exchange chromatography, Science, 186(1974)226. 

Inczedy, Analytical Applications of Ion Exchangers, Pergamon Press, New York, 

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Electrodriven Separation Techniques encompass a wide range of analytical procedures based on several distinct physical and chemical principles, usually acting together to perform the requh ed separation. Example of electrophoretic-based techniques includes capillary zone electrophoresis (CZE), capillary isotachophoresis (CITP), and capillary gel electrophoresis (CGE) (45-47). Some other electrodriven separation techniques are based not only on electrophoretic principles but rather on chromatographic principles as well. Examples of the latter are micellar... 

Confirmation of suspected residue findings relies on the various chromatographic principles of cleanup and determination (GPC, NP-LC, GC), and is further supported by re-analysis of the final extract(s) on a GC stationary phase of different polarity, providing modified selectivity, or by the use of GC with specific mass spectrometric detection [GC/MS or gas chromatography/tandem mass spectrometry (GC/MS/MS)]. 

Pre-concentration methods using online trace enrichment by applying chromatographic principles are also reported [66,69]. As described by Guzman and Meyers [71,72], this can be achieved by incorporating e.g. a solid-phase CE-concentrator tip at the inlet of the capillary. Undesired sample components can be flushed out prior to the CE separation run, providing faster and more specific analyses. Especially in the field of bioanalysis, where sample clean up and pre-concentration of analytes is usually critical, this approach may be preferred. 

In this chapter the three main modes of large-scale chromatographic operation, and combined reaction and separation. Many useful but small-scale chromatographic methods have been omitted, as well as allied separation techniques which combine aspects of chromatographic principles or practice with aspects of adsorption, extraction, sedimentation or electrophoresis. Such is the pace of invention that novel processes related to chromatography are still being developed and described in the literature. 

It is assumed that the reader is familiar with such common chromatographic concepts as efficiency, selectivity, capacity factors, and theoretical plates, and how these parameters affect and effect chromatographic resolution. Excellent descriptions of these general chromatographic principles have been published. Other reviews on various aspects of carbohydrate separations will be cited in the appropriate Sections. 

The most common adsorption systems consist of silica gel or alumina adsorbents in association with an organic solvent system. The adsorbent can exert a considerable influence on the separation of compounds. Alumina and silica gel, for example, have significantly different properties and can result in quite different separations. Activation of the adsorbent also influences sample retention. The presence of water on the adsorbent decreases the adsorbent activity due to blockage of active sites. If large quantities of water are present, a partition system may be set up which may extensively change the retention times due to the different chromatographic principle involved. Table 2.1 compares results obtained for the separation of the insecticide carbaryl (Sevin) and its hydrolysis product 1-naphthol on alumina and silica gel. Comparisons between activation and deactivation are made. The results show that separation of the two components is reversed with the two adsorbents examined. In most cases, activation of the plates caused the/ f values to increase relative... 

The efficient utilization of most, if not all, systematic optimization strategies requires an understanding of basic chromatographic principles. Such an understanding also greatly facilitates the interpretation of the results. 

Sychev, Y. N., Vlasov, L. G., Lapitskh, A. V. Use of gas chromatographic principles for the preparation of iron-free niobium and tantalum chlorides. Issled Obi. Khim. Tekhnol. Minr. Solei Okislov, Akad. Nauk SSSR, Sb. Statei 1965, 238. — Chem. 

Physical Scale The contrast in the physical dimensions of chromatographic systems—already pointed out in Chapter 1—is growing as preparative demands push large columns to greater size [27] and analytical needs drive small columns toward microscopic dimensions [23]. Experimental methods are strongly affected by these scale factors but chromatographic principles change little with size unless linear/nonlinear differences are involved. 

In these methods, the separation is carried out by a chromatographic setup. This setup may use various chromatographic principles for protein separation, and this... 

The first applications of CDs as chiral selectors in CE were reported in capillary isotachophoresis (CITP) [2] and capillary gel electrophoresis (CGE) [3]. Soon thereafter, Fanali described the application of CDs as chiral selectors in free-solution CE [4] and Terabe used the charged CD derivative for enantioseparations in the capillary electrokinetic chromatography (CEKC) mode [5]. It seems important to note that although the experiment in the CITP, CGE, CE, and CEKC is different, the enantiomers in all of these techniques are resolved based on the same (chromatographic) principle, which is a stereoselective distribution of enantiomers between two (pseudo) phases with different mobilities. Thus, enantioseparations in CE are commonly based on an electrophoretic migration principle and on a chromatographic separation principle [6]. 

In this Chapter we briefly consider the production and prompt isolation of the nuclear reaction products. The thermalization of recoils and the synthesis of compounds are discussed in more detail, as is the transportation of thermalized recoils by aerosol particulates to remote equipment for chemical experiments. The separations on chromatographic principles are discussed in Chapter 4. Some basic information about detection and measurement was given in Chapter 1 when describing concrete experiments. 

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