Electrophoresis, thin-layer

Equipment used for thin-layer electrophoresis is practically the same as that used for separations on paper, cellulose acetate and ion exchange papers. Usually cooling is introduced into the equipment. Thus, e.g., a water-cooled flat aluminium (dural, brass) block is insulated by means of a replaceable glass plate or plastic film. The thin-layer plate is located on the insulated block and paper wicks ensure the contact with electrode vessels. A polyethylene sheet is placed between the top of the layer and the lid. This protects the surface of the layer from drops of condensed moisture that condense on the lid. A sheet of plate glass covers the whole chamber. If precoated plastic thin-layer sheets are used, the apparatus of the immersed type can be used [78]. Elution of spots, and the general practice in thin-layer electrophoresis is the same as in thin-layer chromatography. 

Practically all types of commercially available thin-layer plates and precoated sheets can be used silica gel, cellulose, kieselguhr, alumina and glass fibres. It is, perhaps, not necessary to emphasize that both one- and two-dimensional arrangements can be materialized as well as different combinations with chromatography and multidimensional procedures [65]. 

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In view of its rapidity we found thin layer chromatography convenient for identification of the amino acids liberated by the first 20—30 degradation cycles. For identification of PTH-derivatives from additional degradation steps we prefer gas-liquid chromatography because of its merits mentioned above, particularly its greater sensitivity. Several colorimetric reactions and chromatographic systems are available for the identification of those PTH-amino acids which remain in the aqueous phase when the PTH-derivatives are extracted with ethyl acetate 23.24,25,13) our hands, thin layer electrophoresis was found to be satisfactory 26,27)... 

Ahrens, H. Korytnyk, W. Pyridoxine chemistry XXL Thin-layer chromatography and thin-layer electrophoresis of compounds in the vitamin Bg group. Anal. Biochem. 1969, 30, 413-420. 

Of more academic interest is the report of Criddle et al. (C15) that kieselgur (silica gel G) is the best medium for thin-layer electrophoresis, and that of Petrovic and Petrovic (P19), who used a mixture of rice starch and gypsum as the most suitable absorbent for the separation of amino acids. 

FI. Fahie Wilson, M. N., Routine investigation of amino acid patterns in blood serum and urine by thin layer electrophoresis. J. Med. Lab. Technol. 26, 363-370 (1969). 

G23. Grassini, G., Thin-layer electrophoresis. In Thin-Layer Chromatography (G. B. Marini-Bettolo, ed.), pp. 55-68. Elsevier, Amsterdam, 1964. 

N7. Nybom, N., Amino acid analysis by means of thin-layer electrophoresis combined with chromatography. Physiol. Plant. 17, 434-442 (1964). 

W5. Walker, W. H. C., and Bark, M., Separation of urinary and plasma amino acids by two-dimensional thin-layer electrophoresis and chromatography. Clin. Chim. Acta 13, 241-245 (1966). 

The results published are not necessarily specific for a given type of caramel. They may be barely credible for plain caramels. For other caramels, combined analytical methods (chromatography of dilute solutions of caramel foUowed by thin-layer electrophoresis, and size-exclusion chromatography) should be applied. Any proof of identity of caramels (or products of the Maillard reaction in a food) is impossible without application of such complex procedures. For instance, thin-layer chromatography alone fails to distinguish between particular types of caramel. ... 

The introduction of any new analytical technique seems to inspire its indiscriminate application, without use of proper precautions, to a variety of problems, many of which could be solved more quickly by other methods. It should be emphasized that gas-liquid chromatography is not a panacea for all problems in the analysis of carbohydrate derivatives. Fast, efficient resolution of any given mixture of derivatives requires judicious selection from among the methods of countercurrent partition, liquid-liquid chromatography on columns or paper, adsorption chromatography on columns or thin layers, electrophoresis, and gas-liquid chromatography. The last method is, under the appropriate conditions, a powerful addition to the list because of its high efficiency and rapid operation, and the reliability of both the qualitative and the quantitative results. 

Some special technological methods used are - normal pressure liquid chromatography (NPLC), - medium pressure liquid chromatography (MPLC), - high pressure (performance) liquid chromatography (HPLC), -distribution chromatography (e.g., DCCC, RLCC), -preparative thin layer chromatography (PTLC), - thin layer electrophoresis (TLE). 

Migration of the polyanions of polymers 4b, 8b, and 8c to anode has been investigated in an electrical field according to eq (1). In thin-layer electrophoresis diagrams of the sodium salts of the polymers developed on electrophoresis cellulose sheets in a buffer (pH 7.4) (Figure 5),. polymers 8c, 8b, and 4b show one, two, and three bands in the electrophoresis diagrams, respectively. 

Figure 5. Thin-layer electrophoresis diagrams of sodium salts of copolymers at constant 250V for 3h in a buffer solution(pH=7.4) (A) polymer 4b (B) polymer 8b (C) polymer 8c...

Several chromatographic methods exist for the analytical study of sugar nucleotides. These include the ethanol-ammonium acetate systems above and ion-exchange on polyethylene-imine paper (PEI paper) or, better, on PEI-cellulose and ECTEOLA cellulose layers. Paper and thin-layer electrophoresis is also useful, provided that extremes of pH are avoided. As a general... 

Free peptides can be examined by paper electrophoresis or by thin layer electrophoresis as well. If one or more cation forming groups, (amino group, guanidino group, imidazole) are present, electrophoresis in an acidic solvent, such as dilute acetic acid, is most revealing. Compounds with free carboxyl groups are best run under basic conditions to allow differentiation by the number of carboxylate anions. The acidic character of the phenolic hydroxyl in tyrosine should be included in these considerations. 

A recently developed thin-layer electrophoresis system which employs silanized silica gel with a 1-octanol surface coating as support, and aqueous borate as buffer, has been examined for the separation of mono-, oligo-, and poly-saccharides as well as phenolic compounds and other degradation products from the hydrolythermolysls of biomass. As expected, mobility depended upon the ability to complex... 

Figure 2 Thin-layer electrophoresis of uronic acids on silanized silica gel, pretreated with octanol-1 in 0.07 mol I barium acetate solution. Electrophoresis 400V, ISOmin, 16°C. Lanes (1) galactu-ronic acid, (2) mannuronic acid, (3) glucuronic acid, (4) hydrolysate of gum arable (glucuronic acid), (5) hydrolysate of sodium alginate (mannuronic and guluronic acids), (M) mixture of (1-3) and guluronic acid, (H) omega-hydroxymethylfurfural. Sample loading 10 pg of each individual compound. Visualization with naphthoresorcinol-sulfuric acid. Origin indicated.

Oefner P and Scherz H (1994) Capillary electrophoresis and thin-layer electrophoresis of carbohydrates. In Chrambach A, Dunn MJ and Radola BJ (eds.) Advances in Electrophoresis, vol. 7. New York VCH Publications. 

It is imperative at every step to avoid the presence of any foreign matter such as gel fragments, pieces of paper, and cellulose particles in samples digested with proteases or hydrolyzed with acid that are to be analyzed by two-dimensional thin-layer electrophoresis and chromatography. 

Thin-layer electrophoresis on silica-gel plates in the presence of borate-phosphate buffers has provided an efficient means for separating adenosine 3, 5 -phosphate and its metabolites prior to their assay. ... 

As long ago as 1946, Consden, Gordon and Martin [137] carried out electrophoretic separation of a mixture of amino acids and peptides on a thin layer of silica gel. Although this technique was accompanied by no particular difficulties, it could not at first keep up with the development at the same time of paper electrophoresis, which was so extremely simple to carry out [129, 268, 777]. Only in recent years, after Stahl in fundamental work had shown how to prepare and use thin layers of adsorbent, has the idea of thin-layer electrophoresis been taken up again. It has the advantage over paper electrophoresis, that interfering adsorption effects can often be avoided through appropriate choice of adsorbent the scope of the method can thus be markedly broadened. In addition, the more uniform and finer structure of the adsorbent used for thin-layer electrophoresis, compared with filter paper, sometimes leads to better resolution. 

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