TLC plates

Bilayer plates (TLC) 671 Bimodal pore size configuration (SEC) 449... 

Fluorography of TLC Plates. TLC plates were developed in the appropriate solvent system and dried at 50° for 10-15 minutes. 

Two spots corresponding to emetine and cephaeline together with some undetermined spots were detected on TLC plate. TLC patterns of the regenerated plants were remarkably similar to those of the parental plant. 

Planar chromatography type of chromatography where the stationary phase is a flat film in the form of a thin layer of material coated onto a rectangular glass or inert plastic support plate (TLC) or as a paper sheet (PC). The mobile phase moves through the stationary phase by capillary action. 

Opium alkaloids are most commonly estimated by separating them on a chromatographic paper (PC) and/or on a thin layer chromatographic plate (TLC). The former needs a longer time for developing spots than on the silica gel layers of TLC. After the separation of different opium alkaloids with different mobile phase systems of PC and TLC, individual alkaloids are quantitatively measured by eluting the spot and using different procedures, like spot area measurement, spectrophotometry, IR spectroscopy, densitometry, etc. Important methods are described below ... 

The exact chemical composition of a plant extract is not always completely known. Many published papers have tried to identify the compound s structure by coupling chromatography with spectrometric methods. Modern densitometers are able to record the in-situ UVA is spectra of a separated substance on a TLC plate. TLC can also be coupled with other methods in order to enhance the compound identification, e.g., mass spectrometry (MS) or nuclear magnetic resonance (NMR). There is instrumentation available to record the in-situ spectra on the TLC plate, or of the separated substance, removed from the plate together with the layer, and then extracted in a small volume of an adequate solvent. 

Desorption electrospray ionization (DESI) was used to obtain mass spectra of dyes, directly from TLC plates. TLC/DESI fundamentals and applications were demonstrated using rhodamines (6G, B, and 123) and federal food, drug, and cosmetic... 

TLC HPTLC plates TLC plate Acetone/28% NH, (99 1, vA) CHCA MALDl-MS Psychotropic drugs [42] 2... 

Although TLC plates may be prepared in the laboratory, their ready commercial availability generally makes this unnecessary. The plates are produced by mixing the adsorbent with a small quantity of a binder such as starch or calcium sulfate and spreading the mixture as a layer approximately 250 p, thick on the supporting plate. The binder is needed for proper adhesion of the thin layer of adsorbent to the plate. TLC plates should be dried in an oven for an hour or more at 110 °C prior to use, to remove any atmospheric moisture adsorbed on them. This is necessary because the activity of the adsorbent and its effectiveness in separating the components of a mixture are decreased because water occupies binding sites on the surface of the solid. 

Apparatus Capillary pipets, 2-cm x 10-cm silica gel TLC plate, TLC chamber. 

Thalidomide cannot be extracted from acid solution. A solution in N sodium hydroxide can be applied to the plate. TLC can be carried... 

Thin-layer chromatography is a subdivision of liquid chromatography, in which the mobile phase is a liquid and the stationary phase is situated as a thin layer on the surface of a flat plate. TLC is sometimes grouped with paper chromatography under the term planar liquid chromatography because of the flat geometry of the paper or layer stationary phases. 

Figure 6 Positive ion laser desorption mass spectra of triphcnylmethane dyes from a TLC plate. TLC spots (A) gentian violet (B) brilliant green. Adapted from (59).

The successful separation of dipeptide diastereomers has been reported by Wieland and Bende (14), Taschner et al. (15), and Pravada et al. (16) either as the free peptides or as the N-protected methyl esters. Hubert and Dellacherie (5) separated diastereomeric p-nitrophenyl (Np) esters of N-protected di- and tripeptides starting from pure L-methionine and DL-alanine, they synthesized Np-S-L-Met-DL-Ala-O-Np and Np-S-L-Met-L-Met-DL-Ala-O-Np. The separation was achieved on silica gel F254 precoated (Merck) plates. TLC separation of diastereomeric dipeptides has been well documented by Arendt et al. (17) and Lepri et al. (18). 

Method ascending one-dimensional development in a TLC chamber with chamber saturation Plates TLC precoated plates, Chiraipiate (Cat. No. 811 055/056, Macherey-Nagel) size 10 cm x 20 cm, layer thickness 0.25 mm)... 

It is not easy to subject intact phospholipids to silver ion TLC, because the polar head group masks the comparatively small changes in polarity produced by the formation of p/-complexes between silver ions and the double bonds of the unsaturated fatty acids. Nonetheless, Arvidson [60,61] has achieved some valuable separations of phosphatidylcholines by using highly active TLC plates. TLC layers (0.35 mm thick) were prepared with silica gel H (without a binder) and silver nitrate in the proportions 10 3 (w/w), and were air-dried at room temperature (in the dark) for 24 hours initially, then either at 175 C for 5 hours or at 180 C for 24 hours plates prepared under the latter conditions were much more active than those dried at the lower temperature. By utilising... 

N,0-DimethyUiydroxylamine hydrociloride (75) (11.46 g, 117.5 mmol) and sodium acetate are dissolved in water (28 ml) and slowly added to a solution of 2-acetamido-2-deoxy-D-glucose (70) (10 g, 45.2 mmol) in water (38 ml) at 0 °C. The reaction mixture is stirred for 20 h at room temperature, after which the complete conversion can be observed by the appearance of a faster moving spot on a silica plate TLC (DCM MeOH = 5 1, i f = 0.4). The solvent is removed in vacuo, and the crude solid is purified by flash sihca gel column chromatography (DCM MeOH = 8 1), yielding a white crystalline solid (76) (11.35 g, 42.95 mmol, 95%). 

Analysis of iV-acetylchitooligosaccharides by the latroscan procedure has been reported. This system combines the efficiency of plate TLC for separating components and the sensitivity of flame ionization detection." In related work disaccharides derived from heparin and chondroitin sulfate have been analysed by reductive amination with an aminolipid followed by high performance TLC separation and liquid secondary ion... 

TLC is used both for characterization of pure surfactants and for detection of surfactants in complex samples. With modem apparatus, TLC is a reproducible technique for analyzing multiple samples simultaneously and has found a niche in metabolism studies, since it has the advantage that all components of the sample are spread across the surface of a single plate. TLC is often used for the initial separation of surfactants into classes, especially for the separation of nonionics from anionics, as described in Chapter 6. 

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