Thin-layer electrophoresis apparatus

Fig. 57. General view of a thin-layer electrophoresis apparatus (photograph of...

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. 

One of the usual sets of equipment for paper electrophoresis can be used for thin-layer electrophoresis if necessary. Apparatus is, however, commercially available today, developed especially for the purpose (Firms 87, 129, 44). 

Fig. 7.9. Flat-gel horizontal electrophoresis apparatus. Design of Vasu (1969), and reproduced here with details supplied by him. The apparatus is made of Perspex and the base plate (1) is 18.6x13.0x0.5 cm. The vertical pieces (2, 3, 4, 5) are all 3 X 1 X 0.2 mm, and the sides are defined by slats, 12 and 13, respectively 10.8 x 0.5 x 0.3 cm and 11.2 x 0.5 x 0.3 cm, and 14 and 16, which are 20 x 1 x 0.2 cm. The glass upper plate, 15, is 16 x 11 x 0.2 cm. This is placed on top of the base plate, resting on the slats (except the side piece 16) mounted as shown, 14 supported by 4 and 5, which are sealed to the plate. Likewise at the ends, are slats 12 and 13, the former supported by 2 and 3. The slot formers stick to the lower plate, and measure 1.2 X 0.2 X 0.2 cm. The acrylamide solution is poured down an inclined glass plate into the gap, and slat 16 is put in place. After polymerisation, the side slats are eased out with a razor blade and the device is inverted. The end pieces are likewise removed, and sheets of Whatman 6 MM paper are used to make contact with the reservoir, one layer above, another below the gel. After loading, and during the run, the gel is covered with a thin plastic sheet.

Several different supports and numerous designs of apparatus can be used for electrophoresis. The supports can be classified broadly as strips, gels, and thin layers they may be totally inert, or they may have a physical effect on the separation. 

The multistage electrophoretic method has been developed by combining free electrophoresis and multistage extraction and is explored as an improved alternate method for the purification and concentration of cells or macromolecules. The present discussion is restricted to cells and particles. The present design is based on a derivative of the thin-layer multistage extractor design of Albertsson [70] and Treffrey et al. [71] and called ADvanced SEParation apparatus (ADSEP), designed by SHOT, Inc. [42]. 

The general view of an example of such apparatus is in Mg, 57 and, in Fig. 58, a cross-section through the electrophoresis chamber. The thin-layer plates (20 x 20 cm) rest on a water-cooled metal plate. 

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