Thin-layer chromatography visualization methods

The thin-layer chromatography (TLC) method was used for purifying the intermediary products obtained from the synthesis of the oligonucleotide dendrimers. The separations were performed on silica gel plates using various solvent mixtures as mobile phases, e.g., methanol-methylene chloride (1 9, v/v), methanol-chloroform (1 30, 1 9, v/v), hex-ane-dichloromethane (1 3, v/v), hexane-ethyl acetate (3 1, 1 1,4 1, v/v). The separated compounds were visualized in an iodine atmosphere. 

Besides the calculation of the different sulfonated species, it is also possible to determine them directly by chromatographic methods. Separation of the ester sulfonate and the disodium salt is achieved by thin-layer chromatography on silica gel plates. With a solvent mixture of acetone and tetrahydrofuran (90 10 v/v) the disodium salt stays at the start whereas the ester sulfonate has an R value of 0.2. With the more polar solvent 0.1 N H2S04 + methanol + chloroform the ester sulfonate and the disalt have Rf values of 0.36 and 0.14. For visualization, the plate is sprayed with pinacryptol yellow. In UV light (254 and... 

The identification of bromocriptine mesilate in the dosage form can be carried out by thin layer chromatography using Merck plates with dichloromethane/methanol/formic acid 78 20 2 (v/v/v) and subsequent uv-visualization at 254 and 360 nm. Using this method, it is important to only air-dry the spot after application to the plate, since more vigorous evaporation of the solvent will give rise to artifacts (32). 

Additional methods which so far have been of only limited interest for the quantitative study of redistribution equilibria are mass spectrometry (313), Raman (68), and infrared (110) spectroscopy. It can be visualized that methods such as microwave spectroscopy, thin-layer chromatography, or Mdssbauer spectroscopy may be of interest in the near future. 

A. S. Kenyon, P. E. Flinn, and T. P. Layloff, Rapid screening of pharmaceuticals by thin-layer chromatography Analysis of essential drugs by visual methods, J. AOACInt., 78 41 (1995). 

For quantitative analyses in paper and thin-layer chromatography the following evaluation and detection methods are in use (Table 3.2.1) the visual method planimetry — colored substances ... 

We have described an efficient general protocol for assaying catalysis using substrates labeled with the fluorescent tag acridone [98]. In this method, reactions are simply analyzed by thin layer chromatography (TLC). Acridone is a highly photoresistant and intensely fluorescent group whose derivatives behave well on TLC. As little as 1 picomole of an acridone-tagged compound is visually detected under illumination with a simple UV lamp, a detection limit that is 10-100 times lower than that for fluorescein or dansyl derivatives. This method is easi-... 

Electrophoretic separations are currently performed in two quite different formats one is called slab electrophoresis and the other capillary electrophoresis. The first is the classical method ihal has been used for many years to separate complex, high-molecular-mass species of biological and biochemical interest. Slab separations arc carried out on a thin flat layer or slab of a porous semisolid gel containing an aqueous buffer solution within its pores. This slab has dimensions of a few centimeters on a side and, like a chromatographic thin-layer plate, is capable of separating several samples simultaneously. Samples arc introduced as spots or bands on the slab, and a dc electric held is applied across the slab for a fixed period. When the separations are complete, the Held is discontinued and the separated species are visualized by staining in much the same way as was described for thin-layer chromatography in Section 281-2,... 

Thin-layer Chromatography. — A t.l.c. method for the analysis of eleven carbohydrates commonly found in foodstuffs has been described using silica gel plates, which are eluted three times with acetonitrile-water (85 15). The spots were visualized using a diphenylamine dip and estimated spectrophoto-metrically. ... 

There must be hundreds of visualization recipes, some of them highly ingenious, particularly where sequences of several colorimetric or fluorimetric methods have been elaborated to provide highly specific identification of certain compounds. These visualization methods have been gathered into various handbooks on paper and thin-layer chromatography [4, 11-14], and the wealth of applications they contain is far more abundant than can be included here. 

Flinn, P.E. Juhl, Y.H. Layloff, T.P. A simple, inexpensive thin layer chromatography method for the analysis of theophylline tablets. BuU. World Hlth. Org. 1989,67, 555-559. Flinn, P.E. Kenyon, A.S. Layloff, T.P. A simplified TLC system for qualitative and semiquantitative analysis of pharmaceuticals. J. Liquid Chromatogr. 1992,15, 1639-1653. Kenyon, A.S. Flinn, PJi. Layloff, T.P. Rapid screening of pharmaceuticals hy thin layer chromatography Analysis of essential dmgs hy visual methods. J. AOAC Inti. 1995, 78, 41 9. 

Kalasz et al. used spacer to improve separation of radiolabeled metabolites, and the method was called spacer D-TLC. They also constructed specific parameters of DC, especially for calculation of the resolution (Rq), yield (7), loss (L), and efficiency ( ). Displacement of radiolabeled compounds was readily visualized using X-ray film with contact autoradiography. Two-dimensional chromatography can be simply arranged when a planar stationary phase is used. The stationary phase must be rotated 90° after the 1st dimensional development then, the system is ready for the 2nd dimensional run. Elution type of development followed by displacement is an easy and useful means of two-dimensional thin-layer chromatography... 

Inorganic polymers, such as metal hydroxo-polymers, sometimes exhibit strong adsorption onto gel materials or decomposition during elution. Thin-layer chromatography is a powerful method in such a case, because a whole chromatographic zone of a sample compound can be readily visualized and the comparison of various compounds is permitted on the same plate under identical conditions. 

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