Chromatography plates

Place the development solvent (l-propanol ethyl acetatexoncentrated NH4OH, 1 1 1) in the developing tank, and develop the chromatography plate so that the solvent migrates for 12 cm. 

As the solvent begins to soak up the chromatography plate, it first dissolves the compounds in the spot that has been placed on the base line. The compounds present will then be carried up the chromatography plate as the solvent continues to move upwards. How fast the components of a mixture are carried up the plate is determined by (1) how soluble the component is in the solvent and (2) how much the component adheres to the stationary phase. An equilibrium is established in which the components partition themselves between the stationary phase and the mobile phase in a fixed ratio. 

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). 

A thin layer chromatographic method has been developed [117] for the determination of organic compounds capable of cis-trans isomerisation, using dibutyl ethylenedicarboxylate, stilbenzene, azobenzene and azoxybenzene as examples. The civ-isomers were formed from the trans by irradiating solutions with ultraviolet light. For chromatography, plates with a layer of silica gel fixed with gypsum and plates with a... 

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. 

---