An Inexpensive Two-Dimensional Chromatography Apparatus Some experiments which are found in current biochemistry laboratory manuals' call for the use of two-dimenslona1 ascending paper chromatography for the separation and identification of amino acid mixtures or amino acid derivatives. The techniques described involve the use of large beakers, usually 4 I, a s the chromatographic chamber. This procedure works well if the noted precautions are carefully fallowed. The use of the beaker technique becomes rather unhandy if one has a class of greater than about eight students as a large number of beakers becomes necessary. An alternative procedure is the use of pre-cut 25.4 X 25.4 em No. 1 chromatography paper ($3.00/1W) in an apparatus such a s that described by Smith.z Such an apparatus is commercially available with glass chambers and aluminum or polythene paper holding frames and spacers. The price of a complete apparatus currently is between $100 and $140 each. Two chambers is the minimum requirement to eliminate solvent changes. For a larger class a greater number of paper-holding frames would he necessary. To carry out two dimensional paper chromatography experiments without the relatively large investment, one can put together an acceptable apparatus for $20-25 each using high density polyethylene. One-quarter-inch sheet polyethylene is used to construct the chromatographic chamher-a cube, 12 in. on each side. This may be custom fabricated by a supplier such as Bel-Art Products of Pequannoch, N.J., at a very reasonable price. The top covering may he any inert material, preferably transparent (Saran' and Reveal" kitchen covering are acceptable). This may be held in place using a 12 X 12-in. sheet of %in. plywwd with non-rigid foam 1 in. wide glued around the edge of the bottom and placed on top of the covering. The paper support frame is constructed of 4 parts-ends (2 required), rods (4required), nuts (8 required), and spacers (requirement depends upon length of rods and separation required; 1 in. will give adequate separation and allow 8 sheets to be run a t once). The ends are made from 10 X 10-in. sheets of ',-in. polyethylene with a %in. hale drilled in each corner, centered with the hole centers in each corner of the chromatography paper. The rods are made from %-in. high density polyethylene rod 10 in. long threaded h ' in. in on each end with y4 in.-20 threads. Threading the polyethylene is tricky and great care must he taken. Using a lathe, turn the rod ends to 0.238 in. before threading. The spacers are made from %in. 0.d. polyethylene tubing with 'he-in. wall cut to the desired length. The nuts are made by tapping threads (% in.-20) in the center of %/r X %-in. squares of %in. polyethylene. A clean tap should he run through each nut a few times when finished. When using the frame, be sure that the corner of a nut does not extend below the edge placed in the solvent.
'Clark, John M., Jr., (Editor) "Experimental Biochemistry," W . H. Freeman and Co., San Francisco, 1964, p 95, 98. Krogmann. David W., "Molecules, Measurements, Meaninps-A Laboraton, Manual in Biochemistry," W. H. Freeman and Co., San Francisco. 1971, p. 1. Rendena, George, "Experimental Methods in Modern Biochemistry," W. B. Saunders Co., Philadelphia, 1971, p 94. Smith, Ivor, "Chromatograph~eand Electrophoretic Techniques, Volume 1; Chromatography," 3rd Ed., Wiley-Interscience Publishers. New York, 1969, p. 7. Robert W. Soeder Appalachian State University Bwne. North Carolina 28608
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Journal of Chemical Education
