PAPER CHROMATOGRAPHY 



360 



in it without the need of any .special ,supj>ort. This arrangement is show n 

 schematically in Fig. 8-3. 



When sheets are used, two-dimensional chromatograms can be made. 

 This is done by application of the sample at one corner of the sheet and 

 development with solvent in the same way as in the strip or one-dimen- 

 sional method. After development, the sheet is turned at right angles 

 so that the separated spots can be resolved further l)y use of a second sol- 

 vent. As a practical matter, it is most convenient to use two chambers 

 for two-dimensional work, one for each solvent. Wintoringham (lo) has 



H 



(a) (6) (c) 



Fig. 8-4. Procedure for small-scale paper-chromatosraphi(! separations. [From Louis 

 B. Rockland and Max S. Dunn, A Capillary-ascent Test Tube Method for Separating 

 Amino Acids by Filter Paper Chromatography, Science, 109: 539-540 (1949).] 



described a method by means of which the individual zones separated by 

 the first solvent can be concentrated by controlled evaporation and trans- 

 ferred to a fresh strip of paper, which can then be treated for further sep- 

 aration with another solvent. This procerhire permits multidimensional 

 chromatography provided the zones can be identified, as by radioisotopes, 

 without degradation of the separated components. 



A simple procedure for small-scale separations has been described by 

 Rockland and Dunn (16) and is illustrated in Fig. 8-4. About 0. 1 ml of 

 solvent is pipetted into the bottom of a 6-in. test tube. A filter-paper 

 strip is cut so as to be 13.6 cm long, 1.8 cm wide at one end, and 1.0 cm 

 wide at the other. The test substance is applied at about 6 mm from the 

 narrow end, and the paper is dried and then placed in the test tube so that 



