Improved Technique for Two-Dimensional Circular Paper Chromatography PRAMILA Y. GAITONDE and J. W. AIRAN Wilson College, Bombay 7, India The segment-sector combination is presented a s an improvement oyer the ring-disk technique in twodimensional circular paper chromatography. This new technique seems to give better results w i t h amino acids t h a n could be obtained using the conventional two-dimensional circular chromatograms.
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IRCULAR (disk) paper chromatography is now being used on an increasing ' ' scale (2, S, 8 , l O - l Z ) . A method for twodimensional circulas paper chromatography ( 1 has been applied to the separation of certain organio acids (6, 6 ) . This spplioatian and observations regarding the path of a substance in the "ring" during the first run ( 4 )led the present authors to attempt to develop a "combination" ahieh would give a more distinct separation of the arcs themselves rather than of merely the outer tips forming the spiral ( 1). I t was hoped that this would limit the rather extensive spreading of the arcs in such a way as to give only slightly elongated spots.
40 X 10 cm.) with glass slide supports along the inside circumference, on which the paper disk rests; the interior of the box is coated with umx. Micrometer syringe, Agla. (Burroughs, Wellcome & Co., London, England) for spotting. The first stebin this investigation was t o determine the manner in which a substance spreads itself in the ring during the first run. This was done by applying phenylalanine solution to six rings and developing them in separate chambers so that any one of the rings could be removed as soon a6 the solvent front had reached a desired point an the ring. After spraying with ninhydrin, the shape developed hy the amino acid when it had traversed the given distance in the ring could be noted. The amino acid showed a sickle shape when i t had traversed the maximum distance in the ring, the advance point curling inwards, the tail end thinning out into the solvent, and the middle portion (which touched the outer rim of the ring) showing the maximum color density. Such B far-flung spat in the ring would obviously give, in the combination, an arc even,more extensively spread out, 8 s it does in practice. In spite of its sickle shape in the ring, this arc is fairly uniform, a point which prompted certain other experiments. A single amino mid wa6 applied a t three adjacent points which were at sliehtlv uneaual distances from the source of the solvent. For this e&e
