Thin-layer chromatography plates

Occasionally use several drops to spot, develop, and visualize a thin layer chromatography plate. Although thin layer is very similar to column, you should read up on it as 1 do not have time to go into the complete operation. 

In our laboratory crude preparations of aphantoxins and anatoxin-a(s) are extracted similarly except at the final stages of purification (Fig. 2). A Bio-gel P-2 column (2.2 x 80 cm) is used for aphantoxins gel filtration and a Sephadex G-15 (2.6 x 42 cm) column for ana-toxin-(s). Both toxins are eluted with 0.1 M acetic acid at 1.5 ml/ min. Fractions of aphantoxins from Bio-gel P-2 run are spotted on thin-layer chromatography plates (Silica gel-60, EM reagents) and developed according to Buckley et al. (1976) (31). The Rf values for the aphantoxins, saxitoxin and neosaxitoxin standards (Table 1) indicates that two of the aphantoxins (i.e. I and II) are similar to saxitoxin and neosaxitoxin. 

E. Merck cellulose thin-layer chromatography plates (available from American Scientific Products) are developed with chromatography buffer (Note 13) and visualized with sulfosalicylic acid/ferric chloride spray. The system consists of a solution of 1.0 g of sulfosal icyl ic acid (from Aldrich... 

A diagram of a typical thin-layer chromatography plate after development and spraying to locate the analytes is shown in Figure 13.2. 

Figure 9.29 Membrane formation by meteoritic amphiphilic compounds (courtesy of David Deamer). A sample of the Murchison meteorite was extracted with the chloroform-methanol-water solvent described by Deamer and Pashley, 1989. Amphiphilic compounds were isolated chromatographically on thin-layer chromatography plates (fraction 1), and a small aliquot ( 1 p,g) was dried on a glass microscope slide. Alkaline carbonate buffer (15 p,l, 10 mM, pH 9.0) was added to the dried sample, followed by a cover slip, and the interaction of the aqueous phase with the sample was followed by phase-contrast and fluorescence microscopy, (a) The sample-buffer interface was 1 min. The aqueous phase penetrated the viscous sample, causing spherical structures to appear at the interface and fall away into the medium, (b) After 30 min, large numbers of vesicular structures are produced as the buffer further penetrates the sample, (c) The vesicular nature of the structures in (b) is clearly demonstrated by fluorescence microscopy. Original magnification in (a) is x 160 in (b) and (c) x 400.

Lane and Katz reported in 1977 that the dark reaction of BaP deposited on the surface of glass Petri dishes with air containing 200 ppb of ozone was fast, with a half-life of —38 min. Katz and co-workers (1979) exposed nine PAHs on thin-layer chromatography plates of cellulose in the dark to 200 ppb of O, in air and found pronounced differences in their reactivities, e.g., half-lives of 36 min for BaP, 2.9 h for BaA, 7.6 h for BeP, and 53 h for benzol b ]fluoranthene. Subsequently, in good agreement with Lane and Katz, a half-life of -1 h was determined for BaP deposited on glass fiber filters and exposed (passively in a controlled atmosphere) to 200 ppb of 03 in the dark (Pitts et al., 1980). 

TLC plate 20 cm x 20 cm x 250 jam silica gel 60 F254 thin-layer chromatography plates (EM Science)... 

Leblanc, C.J., W.M. Stallard, P.G. Green, and E.D. Schroeder. 2003. Passive sampling screening method using thin-layer chromatography plates. Environ. Sci. Technol. 37 3966-3971. 

B. Basak, U. K. Bhattacharyya, and S. Laskar, Spray reagent for the detection of amino acids on thin layer chromatography plates, Amino Acids, 4 193(1993). 

Thin-layer chromatography plates (silica) and spotters... 

Diacetates. The alkenylglycerols are isolated by thin-layer chromatography on silica gel G in a solvent system of hexane-diethyl ether (80 20, v/v). These compounds can be located by use of the TNS spray or by running an additional thin-layer chromatography plate for charring with sulfuric acid. 

The mobile phases used in the development of thin-layer chromatography plates are usually combinations of organic and aqueous solvents. Ethanol, t-amyl alcohol, acetonitrile, and methanol are commonly used organic solvents. Acetic acid is the most commonly used aqueous solvent. In normal-phase partition chromatography the polar stationary phase is developed with relatively nonpolar mo-... 

Silica-gel thin-layer chromatography plates (Fisher catalog 05-713-317) pH paper (1-11)... 

Spot 3 pi of each of the amino acid standards along the origin. As with the thin-layer chromatography plate, spot each sample 1 /u.1 at a time. Indicate the identity of each sample spot below the origin using a soft lead pencil. 

Obtain a silica-gel thin-layer chromatography plate that has been activated in a 100°C oven for 5 to 10 min. On either side of the plate, make a small scratch in the silica matrix about 2 cm from the bottom of the plate. This will mark the position of the origin, along which the samples will be spotted. Do not mark on the plate with pencil. 

Analyze your thin-layer chromatography plate. What lipids displayed the lowest and highest Rf values Explain the reason for this result in terms of the chemical nature of the stationary and mobile phases used in this experiment and the nature of the different molecules being separated in this experiment (which lipids would you expect to show the greatest and the least mobility on the plate and why). 

Silica-gel thin-layer chromatography plates (Fisher catalog 05-713-317)—Heat at 100°C for 10 min just before use. (Store dessicated at room temperature.) Twenty-five will be required we try to fit two groups on one plate. 

Silica-gel thin-layer chromatography plates—We purchase these from Fisher (catalog 05-713-317). The plates are prepared (activated) by heating in a 100°C oven for 5 to 10 min to remove any moisture from the matrix. Remove from the oven and store desiccated at room temperature until they are ready to be used. Approximately 2 5 plates will be required (1 plate/2 groups). 

I2 Chamber—Fill the bottom of a rectangular glass chamber with I2 (solid) and cover tightly. Allow 6 to 8 hr for the chamber to saturate with I2 vapors before the thin-layer chromatography plates are developed. 

Small quantities of compounds in natural extracts are often a problem when these need to be evaluated in bioassays. Sometimes there is just not enough of the compound isolated to carry out the usual bioassay.20 Microassays have been developed10 1 to overcome this problem. Typically, a microassay is carried out on a thin-layer chromatography plate with a cellulose layer. A small droplet (1.5 pi) of the tested compound in a solvent (1-102 nmol cm-2) is then added on the plate. After the solvent has evaporated a small amount (5 pi) of sucrose solution lmoll-1 is added to the place where the compound was added. In the control the same procedure was followed on a different plate, but with the solvent alone, with no compound added. These two plates are then placed in a petri dish with the test insect species. In the past, when paper chromatography was widely used, a crude plant extract was placed on the origin of the paper and then eluted into bands. The paper was freed of solvent, sprayed with sugar solution, and used directly in a bioassay to see which parts of the paper were not eaten, and therefore of interest for further examination. 

Apply the mixture of compounds as a dichloromethane solution to a preparative thin-layer chromatography plate using a syringe. Allow the plate to air-dry, and then elute it with ethyl acetate. 

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