METHOD FOR DECOLORIZING CHROMATOGRAPHY SOLUTIONS JACK RADELL and P. D. HUNT Wright-Patterson Air Force Base, Ohio D E C O L ~ R I Z ~ofG a solution of an organic componud prior to chromatography requires heating the prepared solution with carbon black or carbon black and filter aid. The heated solution is filtered and then added to the chromatographic column. The collected fractions are concentrated to recover the organic compound. Some of the shortcomings of this method result from the number of transfers required and the difficulty of completely filtering off carbon. Consequently significant quantitative information is more difficult to obtain. In this laboratory a dry packing procedure has been employed which considerably eliminated the above difficulties. The adsorbent ( A ) is added with tapping and periodic tamping until the desired length of column is obtained. The adsorbent is covered by a layer of absorbent cotton ( B ) followed by a layer of intimately mixed activated carbon: filter aid' ( 3 : l by vol.) ( E ) another layer of cotton (C) and finally a
layer of purified sand (D). The sand is used to prevent the cotton from floating up ~vhenliquid is added. The decolorizing layer (E)should not be more than onetenth the length of adsorbent. The effluent from the colnmn is fed directly into a continuous concentration apparatus through a cork stopper ( F ) . This consists of a 3-way connecting tube (G) leading to the tared concentration flask (H). The third connection carries the distilled developer to the combined condenser and analytical still head (I)from which it is collected in a graduated cylinder (J). The conrentration flask was heated by a constant level hot nater bath (K) on a hot plate (L). When a fraction is ready for remhval, the bottom end of the column is corked for 10 minutes to assure complete removal of the developer. The developer may he fed into the column by a constant level device (M) prepared from a 5-mm. i.d. tube sealed on to the neck of a single necked round bottom flask filled with developer and supported so that the end of the tube is a t the desired liquid level in the column above the sand. This procedure may be modified so that developers boiling above 100°C. can be removed by an appropriate constant temperature bath. If it mere desirable the adsorbent could be added to the column by one of the wet-pack methods. The dry-pack method using FlorisilZ as an adsorbent has been found most convenient in this laboratory. The proposed method has a number of advantages over some more common practices. After the solution to be decolorized and chromatographed is added to the column, no transfers are required. Thus reliable quantitative data are easily obtained. In fact, traces of material can be isolated easily from a large volume of developer with no losses. The apparatus once in operation requires little care. Overheating of the residue obtained by evaporation is minimized by the hot water bath. When a fraction is removed, the volume of developer distilled can be read directly in the graduated cylinder and the weight of residue can be obtained promptly by weighing the tared concentration flask.
' A suitable filter aid is Celite Analytical Filter-Aid, manufactured by the Johns-Manville Co., New York, N. Y . a A product of the Floridin Company of Tallahassee, Florida.
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