. Carotenoids. Carotenoids; Carotenoids. SEPARATION OF THE CAROTENOID MIXTURES 27 from the excellent work of Hesse', is one of decreasing adsorptive capacity of the solutes: petroleum ether, carbon tetrachloride, trichloroethylene, benzene, methylene dichloride, chloroform, ether, ethyl acetate, acetone, w-propyl alcohol, ethanol, methanol, water, pyridine. -Adsorbent 'Glass tube Cottonwool Rubber stoppers Experimental. A suitable adsorbent and solvent, and the size of the chromatogram column, are first selected by means of preliminary small-scale experiments. The chro- matogram tube is then f
. Carotenoids. Carotenoids; Carotenoids. SEPARATION OF THE CAROTENOID MIXTURES 27 from the excellent work of Hesse', is one of decreasing adsorptive capacity of the solutes: petroleum ether, carbon tetrachloride, trichloroethylene, benzene, methylene dichloride, chloroform, ether, ethyl acetate, acetone, w-propyl alcohol, ethanol, methanol, water, pyridine. -Adsorbent 'Glass tube Cottonwool Rubber stoppers Experimental. A suitable adsorbent and solvent, and the size of the chromatogram column, are first selected by means of preliminary small-scale experiments. The chro- matogram tube is then filled with the adsorbent. A variety of more or less complicated arrangements for large-scale chromatography have been de- scribed. Only a very simple apparatus which is readily as- sembled, inexpensive, and adequate for all purposes will be described here. It consists of a suction flask, a short glass tube ca. 10 mm in diameter and two good rubber stoppers. The stoppers are arranged back-to-back on the glass tube; one stopper is placed in the suction flask and the other in the chromatogram tube, as shown in the accompanying figure. The filling of the tube with the adsorbent can be carried out in various ways. The usual procedure is to add a small amount of the adsorbent at a time and to press it down with a half-bored cork attached to a glass rod. For larger tubes, Zechmeister recommends a wooden stopper, the end of which has a diameter corresponding to two-thirds of that of the tube. After one layer has been well pressed down, more adsorbent is added and the operation is repeated until the tube is suffi- ciently full. It is important that the tube should be well and evenly filled, otherwise distorted colour-zones are obtained which are difficult to separate. When the tube has been filled, the vacuum is connected and the pressing and tapping (from the outside) is continued until the adsorbent no longer moves. If this is done, no shrinking should occur when solvent is added. WiN
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