Thin layer chromatography electrophoresis

TWO-DIMENSIONAL SEPARATION BY THIN-LAYER CHROMATOGRAPHY/ ELECTROPHORESIS... 

Several physical methods have been developed for the determination of papaverine, viz. spectrophotometry, titration in non-aqueous media, thin-layer chromatography, electrophoresis, planimetry, " and oscillo-polarography. ... 

Because of the instability of many of the compounds involved, it is necessary to determine the chemical recoveries in all cases. This requires the use of macro quantities (10 mg up to several hundred mg) of carriers and target compounds. This, in turn, makes it impractical to use the various thin-layer methods, such as paper and thin-layer chromatography and paper electrophoresis, although such methods have proved useful in identifying products and in checking the purity of fractions. The separation methods now most commonly used are column chromatography and sublimation. 

Thin-layer chromatography (TLC) is a type of liquid chromatography in which the stationary pease is in the form of a thin layer on a flat surface rather than packed into a tube (column). It is a member of a family cf techniques that include some types of electrophoresis and paper chromatography, more generally referred to as planar chromatccraphy. Since we will not discuss electrophoresis in this section, and since TLC has virtually superseded paper chromategr pby in most analytical... 

Pereira, A., Pereira, M, M., Free amino acids in green coffee from Huambo (Angola). Separation and identification by electrophoresis and thin layer chromatography, Coll. Sc 1. Int. Cafe, 8, 545, 1977. (CA92 196460s)... 

Rowe, K., Bowlin, D., Zou, M., Davis, J.M. (1995). Application of 2-D statistical theory of overlap to three separation types 2-D thin-layer chromatography, 2-D gas chromatography, and liquid chromatography/capillary electrophoresis. Anal. Chem. 67, 2994. 

This effect is illustrated in Fig. 17.1. Multidimensional chromatography separations can be done in planar systems or coupled-column systems. Examples of planar systems include two-dimensional thin-layer chromatography (TLC) (Consden et al., 1944 Grinberg et al., 1990), where successive one-dimensional TLC experiments are performed at 90° angles with different solvents, and 2D electrophoresis, where gel electrophoresis is run in the first dimension followed by isoelectric focusing in the second dimension (O Farrell, 1975 Anderson et al., 1981 Celis and... 

Adsorption chromatography Size exclusion chromatogaphy Thin-layer chromatography Gas chromatography Electrophoresis... 

If the compound shows no convenient intrinsic feature, it may be possible to develop a detectable characteristic by chemical modification and, particularly in thin-layer chromatography and electrophoresis, many locating reagents which are specific for various groups of compounds are available. 

The inclusion of a fluorescent dye into thin-layer plates can be used to detect substances that quench its fluorescence and so result in dark zones when the chromatogram is examined under ultraviolet radiation. Autoradiography can also be used in thin-layer chromatography and electrophoresis when samples are radio-labelled. 

The identification and quantitation of the individual amino acids in a mixture is often required in metabolic studies and investigations of protein structure. The use of thin-layer chromatography or electrophoresis may be adequate to indicate the relative amounts and number of different amino acids in a sample but the use of gas-liquid chromatography or an amino acid analyser is essential for quantitative analysis. 

This review provides an overview of the literature published to date on macrocyclic antibiotics exploited for enantioselective separations in high-performance liquid chromatography (HPLC). It was not intended as a comprehensive issue on the applications of such antibiotics in sub- and supercritical fluid chromatography (SFC), thin layer chromatography (TLC), capillary electrophoresis (CE), and capillary electrochromatography (CEC). A number of structural properties of the most important macrocyclic antibiotics applied in HPLC enantioseparations are listed in Table 2.1. 

Novatchev, N., and Holzgrabe, U. (2002). Comparison of the suitability of capillary electrophoresis and thin-layer chromatography for determination of impurities In amino acids. Pharmeuropa 14(4), 640-647. 

The only method that can be used routinely to identify organoas-tatine compounds is measurement of radioactivity based upon its distribution over two or more phases. Such techniques are gas-liquid chromatography (GLC), high-pressure liquid chromatography (HPLC), thin-layer chromatography (TLC), and electrophoresis. 

Owing to the polar and nonvolatile nature of most compounds used as medicinal drugs, reversed-phase HPLC is the most common technique for monitoring the dmg substance and its impurities. GC is also used, particularly for residual solvents, and capillary electrophoresis (CE) has been introduced in more recent times. Some older methods use thin-layer chromatography (TLC), but use of this methodology for the quantitative measurement of impurities is not common. 

Thin-layer chromatography (75) and sodium dodecylsulfate-(poly)acrylamide gel electrophoresis (SDS-PAGE) are helpful for analyses of the lipid and protein composition, respectively. Size-exclusion chromatography allows estimation of the size distribution of the (proteo)liposomes and crude fractionation of the material as reviewed in Ref. 76. Accurate determinations of size distributions require analyses by static or dynamic... 

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