Mobile phase analytical thin-layer chromatography

Bodoga, R, Marufoiu, C., and Coman, M.-V., Faze mobile (mobile phases), in Cromatografia pe Strat Sublire. Analiza Poluanlilor (Thin-Layer Chromatography. Pollutant Analysis), Analytical chemistry series. Technical Publishing House, Bucharest, 1995, chap. 3 and references cited therein. 

Thin Layer Chromatography is a valuable analytical technique. It is cheap, fast and simple. Optimization of TLC is therefore of the highest importance and subject of many studies. A review of optimization methods is given by Nurok [1]. The aim of such optimizations is to find a mobile phase composition at which a good separation of all solutes is possible. However, not only the mobile phase has influence on the retention time, but also the temperature and the relative humidity. 

Thin-Layer Chromatography. Thin-layer chromatography (lie) offers several advanlages for chiral separations and in Ihc development of new chiral stationary phases. Besides being inexpensive, tic cun be used lo screen mobile phase conditions rapidly (i.e organic modifier content. pH. etc.), chiral selectors, and analytes. Several different analytes may be run simultaneously on Ihe same plale. Usually, no preequilibralion of the mobile phase and stationary phase is required. In addition, only small... 

Paper and thin layer chromatography (TLC) are essentially analytical techniques that can also be used semi-preparatively. The paper or thin layer material serves as the solid phase and the mobile phase is the solvent, or mnning buffer, which is transported along the stationary phase by capillary forces. We discuss here only thin layer chromatography (Grinberg 1990 Touchstone 1992) which has superseded paper chromatography in almost all applications. 

Thin-layer chromatography (TLC) in which a glass or plastic plate is coated with a thin layer of the stationary phase and the mobile phase ascends the plate by capillary action. TLC is essentially an analytical tool and preparative TLC has been largely superseded by flash chromatography. 

Measurement of labelling yield and subsequent radiochemical purity requires a suitable analytical technique, and the method of choice for radio-labelled peptides is reversed phase HPLC with on-line UV and radiometric detection. It is important to use as stringent a separation method as possible with isocratic or slow mobile phase composition gradients over the peptide peak. Ideally, more than one mobile phase system should be used (e.g. a phosphate buffer-methanol system in addition to the standard water-acetonitrile system), since these may show the presence of new impurities. It is important to recognize that HPLC analyses only measure those components that elute from the column. Insoluble, highly lipophilic or positively charged species may bind to the solid phase. It is very important to verify the absence of these species by a complimentary technique such as thin layer chromatography (TLC) and to ensure that the two techniques produce similar results. 

Novel analytical techniques such as forced-flow planar chromatography (FFPC) and optimum pressure laminar chromatography (OPLC) are other additions to ever-refined tools for separation on a preparative scale, wherein small amounts of complex mixtures may be separated more efficiently on thin-layer chromatography plates operating at fast medium-pressure development with continuous collection of mobile phase at the end of chromatographic plates (Nyredy, 20(X), 2003). 

Hinze, WL, DY Pharr, ZS Fu and WG Burkert (1989). Thin-layer chromatography with urea solubilized beta.-cyclodextrin mobile phases. Analytical Chemistry, 61(5), 422 28. 

Two-dimensional analytical techniqnes can combine two similar (e.g., 2D thin-layer chromatography [TLC] [cf. Section 11.3] or 2D gel electrophoresis [cf. Section 11.3]) separation procedures by sequentially varying the mobile phase compositions and developing with the second phase in a direction perpendicnlar to the hrst. 

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