Chromatography liquid solid

For most samples liquid-solid chromatography does not offer any special advantages over liquid-liquid chromatography (LLC). One exception is for the analysis of isomers, where LLC excels. Figure 12.32 shows a typical LSC separation of two amphetamines on a silica column using an 80 20 mixture of methylene chloride and methanol containing 1% NH4OH as a mobile phase. Nonpolar stationary phases, such as charcoal-based absorbents, also may be used. 

Example of the application of liquid-solid chromatography to the analysis of amphetamines. (Chromatogram courtesy of Alltech Associates, Inc. Deerfield, IL). 

Liquid-solid chromatography (LSC). This process, often termed adsorption chromatography, is based on interactions between the solute and fixed active sites on a finely divided solid adsorbent used as the stationary phase. The adsorbent, which may be packed in a column or spread on a plate, is generally a high surface area, active solid such as alumina, charcoal or silica gel, the last... 

EC = ion exchange chromatography IPC = ion pair chromatography LSC = liquid—solid chromatography... 

The vast majority of modem liquid chromatography systems involve the use of silica gel or a derivative of silica gel, such as a bonded phase, as a stationary phase. Thus, it would appear that most LC separations are carried out by liquid-solid chromatography. Owing to the adsorption of solvent on the surface of both silica and bonded phases, however, the physical chemical characteristics of the separation are more akin to a liquid-liquid distribution system than that of a liquid-solid system. As a consequence, although most modern stationary phases are in fact solids, solute distribution is usually treated theoretically as a liquid-liquid system. 

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. 

Liquid-solid chromatography (LSC), sometimes referred to as normal phase or straight phase chromatography, is characterized by the use of an inorganic adsorbent or chemically bonded stationary phase with polar functional groups and a nonaqueous mobile phase... 

Figure 4.27 Flow chart for coluwi selection based on sample type (m - molecular weight). PLC precipitation-liquid chromatography SEC = size-exclusion chromatography lEC - ion-exchange chromatography HIC hydrophobic interaction chromatography LSC liquid-solid chromatography RPC - reversed-phase liquid chromatography BPC (polar) bonded-phase chromatography and IPC - ion-pair chromatography.

In NPLC, which refers to the use of adsorption, i.e. liquid-solid chromatography (LSC), the surface of microparticulate silica (or other adsorbent) constitutes the most commonly used polar stationary phase normal bonded-phase chromatography (N-BPC) is typified by nitrile- or amino-bonded stationary phases. Silica columns with a broad range of properties are commercially available (with standard particle sizes of 3, 5 and 10 im, and pore sizes of about 6-15nm). A typical HPLC column is packed with a stationary phase of a pore size of 10 nm and contains a surface area of between 100 and 150m2 mL-1 of mobile phase volume. 

LAMS Laser(-assisted) mass spectrometry LSC Liquid-solid chromatography... 

Liquid silicone rubber (LSR), 22 584 Liquid silicon, properties of, 22 484t Liquid soaps, 22 748 Liquid soil detergency, 8 422-423 Liquid—solid chromatography, adsorption, 1 610-611... 

For example, hexane (see Table 15.1) can be injected as a sample to determine t0 if chloroform is being used as the mobile phase in liquid-solid chromatography. As long as the flow rate of the mobile phase through the column remains unchanged, t0 is the same for any mobile phase. If flow rate changes by some factor x, t0 will change by the factor 1/x. 

Analysing volatile acids in aqueous systems, resulting mainly from the presence of water, have been reported [19]. The volatile acids high polarity as well as their tendency to associate and to be adsorbed firmly on the column require esterification prior to gas chromatographic determination. The presence of water interferes in esterification so that complex drying techniques and isolation of the acids by extraction, liquid solid chromatography, distillation, and even ion exchangers had to be used [20-23],... 

Mangani et al. [13] used Carbopack B columns to recover chlorinated insecticides in soil samples. These workers noted that, although the principles governing the adsorption and extraction process in the extraction in soil analysis are the same as those that govern liquid-solid chromatography, the main feature of a chromatographic column, i.e. separation efficiency, is almost completely absent. 

LSC is liquid-solid chromatography. Strictly speaking, any type that utilizes a solid stationary phase, namely, adsorption, ion exchange, and size exclusion, can be referred to as LSC. However, adsorption chromatography is the only one of this group that is routinely referred to as LSC. 

Glajch, J.L. and Snyder, L.R. (1981), Solvent Strength of Multicomponent Mobile Phases in Liquid-Solid Chromatography. Mixtures of Three or More Solvents, J. Chromatogr., 214, 21-34. 

Liquid-Solid Chromatography (LSC) Data and Reverse Osmosis... 

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