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Chromatography, general column-liquid

The application of pressure to the liquid phase in liquid chromatography generally increases the separation (see HPLC). Also in PIC improved efficiency of the column is observed if pressure is applied to the mobile phase (Wittmer, Nuessle and Haney Anal Chem 47 1422 1975). [Pg.21]

In addition to water, virtually any organic polar modifier may be used to control solute retention in liquid-solid chromatography. Alcohols, alkyl2aiines, acetonitrile, tetrahydrofuran and ethyl acetate in volumes of less than one percent can be incorporated into nonpolar mobile phases to control adsorbent activity. In general, column efficiency declines for alcohol-moderated eluents cogqpared to water-moderated eluent systems. Many of the problems discussed above for water-moderated eluents are true for organic-moderated eluents as well. [Pg.198]

A schematic diagram of a chromatograph for SFC is shown in Figure 6.10. In general, the instrument components are a hybrid of components developed for gas and liquid chromatography that have been subsequently modified for use with supercritical fluids. Thus, the. fluid delivery system is a pump modified for pressure control and the injection system a rotary valve similar to components used in liquid chromatography. The column oven and... [Pg.832]

Liquid-liquid adsorption chromatography (adsorption column) a Flurosil b Alumina c Silica gel d Nuchar carbon Fats, phospholipids, pigments, polar impurities General... [Pg.120]

Unlike high-performance liquid chromatography (HPLC), there is no maximum length for capillaries in CEC, but the longer columns mean slower chromatography and equilibration. Generally, columns in CEC are no longer than 60 cm. [Pg.262]

For chromatography to occur, a mobile phase and a stationary phase are needed. The mobile phase is a gas in gas chromatography and is a liquid in liquid chromatography. In GC, the stationary phase is almost always a column of liquid, gum, or elastomer but not a solid, while in LC the stationary phase is generally a column of a porous solid. Strictly, the names should be gas liquid chromatography (GLC) and liquid solid chromatography (LSC), as will be found in the early literature. The shortened names (GC, LC) came into use through widespread... [Pg.245]

This chapter will discuss planar chromatography and column chromatography in general. The more advanced techniques such as gas chromatography (GC) and high performance liquid chromatography (HPLC) will be discussed extensively in subsequent chapters. [Pg.2]

As far as liquid phase chromatography on columns is concerned it is probably true to say that the division into adsorption and partition methods is of practical, rather than theoretical, significance. The importance of adsorption varies from system to system and is mentioned briefly in connection with the different supports described below. The moving phase in partition chromatography may be a liquid or a gas, and the general principles are the same in each case. [Pg.124]

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See also in sourсe #XX -- [ Pg.9 ]



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