Planar thin-layer

Nyiredy, Sz., Preparative planar (thin-layer) chromatography, in l.D. Wilson, E.R. Adlard, M. Cooke, and C.E Poole, Eds., Encyclopedia of Separation Science, Academic Press, London, 2000, pp. 888-899. 

Planar Thin layer Ascending, descending, radial Adsorption, partition, ion exchange, size exclusion... 

Both biopolymers and noncovalent polymers are produced at the borderline between hydrophobic membrane structures and bulk water. The hydrophobic effect enforces curvature in both, hydrogen bonds lead to linear chains, chirality produces helices, sheets are often insoluble and are applied only occasionally. All kinds of planar thin layers occur, however, on solid surfaces, e.g., bones and minerals in nature or gold, graphite and mica in model systems. 

The radial separation in the earlier example is not the most efficient way to perform surface chromatographic separations. A square planar thin-layer chromatography (TLC) plate (not to be confused with the theoretical plates discussed previously ) may have a line of spots containing sample mixtures and reference standard materials deposited just above one edge. Submerge that edge in solvent to a level just below the line of spots, and capillary attraction... 

Beside the conventional use of the TLC-MS interface, performing the direct connection to the MS by a capillary from the outlet line of the interface to the MS, a further very promising option to couple planar thin-layers to MS is realized by integrating an HPLC column between the thin-layer plate (directly after the TLC-MS interface) and the MS (Figure 10.1a). 

PLANAR THIN LAYER GEL PERMEATION CHROMATOGRAPHY fTLGPC)... 

Geiss, F. Fundamentals of Thin Layer Chromatography (Planar Chromatography). Huthig-Verlag, Heidelberg-Basel-New York 1987. 

Unquestionably, most practical planar chromatographic (PC) analytical problems can be solved by the use of a single thin-layer chromatographic (TLC) plate and for most analytical applications it would be impractical to apply two-dimensional (2-D) TLC. One-dimensional chromatographic systems, however, often have an inadequate capability for the clean resolution of the compounds present in complex biological samples, and because this failure becomes increasingly pronounced as the number of compounds increases (1), multidimensional (MD) separation procedures become especially important for such samples. 

S. K. Poole and C. F. Poole, Evaluation of the separation performance of Empore thin layer chromatography sheets , 7. Planar Chromatogr. 2 478-481 (1989). 

J. W. Hofsti aat, S. Griffioen, R. J. van de Nesse and U. A. Th Brinkman, Coupling of naiTOw-bore column liquid cliromatography and thin-layer cliromatography. Interface optimization and characteristics for normal-phase liquid cliromatography , J. Planar Chromatogr. 1 220-226 (1988). 

Two-dimensional planar eleetrophoresis was first used in 1951 (8), while eleetrophoresis was eoupled with thin-layer ehromatography (TLC) in 1964 to separate mixtures of nueleosides and nueleotides (9). These teehniques were novel and led to other great diseoveries, but did not survive the test of time, and they are no longer eommonly used. TLC-eleetrophoresis in partieular was an awkward teehnique to... 

Graphite is planar, with the carbon atoms arranged in a hexagonal pattern. Each carbon atom is bonded to three others, two by single bonds, one by a double bond. The hybridization is sp2. The forces between adjacent layers in graphite are of the dispersion type and are quite weak. A lead pencil really contains a graphite rod, thin layers of which rub off onto the paper as you write (Figure 9.13, p. 242). 

The most widely used amperometric detectors are based on the thin-layer and wall-jet configurations (Figure 3-22). The thin-layer cell relies on a thin layer of solution that flows parallel to the planar electrode surface, which is imbedded in a... 

Tubular Planar (parallel flow) Thin-layer cell Planar (perpendicular) Wall-jet detector 1= 1.61 nFC(DA/r)2/3U123 i = 0.68 nFCD2l3v- 6(A/b)V2UV1 i = 1.47 nFC(DA/b)2/3U123 i = 0.903nFCD2f3v- 6A3/4u 2 i = 0. mnFCD2/3v-5/ua-V2A3/tU3/4... 

The identification of the target colorant is done directly by UV-Vis spectrometry (if the colorant is unique) or by a previous separation from a mixture. The most available techniques are planar chromatography (paper chromatography and thin layer chromatography) and, especially, high performance liquid chromatography... 

Fig. 10. Flow-through electrochemical cell designs. I, Planar geometries, thin-layer (A) and wall-jet (B) flow cell designs. II, Cylindrical geometries, open tubular (A), wire in a capillary (B), and packed-bed (C) flow cell designs...

Modem planar chromatography is suitable not only for qualitative and quantitative analysis but also for preparative purposes. The separation efficiency of a thin-layer chromatographic system is independent of this intended purpose and is mainly determined by the quahty of the stationary phase, that is to say, by the applied coated layer. Therefore, progress in modem planar chromatography can be attributed not only to the development of the efficiency of the instmments but also to a large extent to the availability of high-quahty precoated layers. And today, as in the past, bulk sorbents for self production, especially of preparative layer chromatography (PLC) layers, are widely used. 

Touchstone, J.C. and Dobbins, M.F., Preparative thin layer chromatography, in Practice of Thin Layer Chromatography, John Wiley Sons, New York, 1978, chap. 12. Nyiredy, Sz., Ed., Planar Chromatography, A Retrospective View for the Third Millennium, Springer Scientific, Budapest, 2001. 

FIGURE 6.7 Cross section of ES chamber with funnel distributor (modified by Wang et al.) 1 — spacing plate, 2 — base plate, 3 — distributor, 4 — glue, 5 — slide, 6 — thin-layer plate, 7 — cover plate. (From Lan, M., Wang, D., and Han, J., J. Planar. Chromatogr. 16, 402-404, 2003. With permission.)... 

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