CHROMATOGRAPHY 159 



Gas chromatography 



The most recent major development is gas chromatography, a separa- 

 tion of materials in the vapor phase. A tube is packed with a solid ma- 

 terial which is then coated with a selected solvent. In another system, 

 the solvent forms a thin coating on the inner walls of a long, very fine 

 capillary tube. In either case, a mixture of gases is allowed to pass through 

 the tube. Those components which are least attracted to the solvent ap- 

 pear earliest at the far end of the tube, the other components appearing 

 later. As the individual gases emerge they are detected by a device that 

 measures thermal conductivity or some similar physical property. The 

 amount of each component is recorded electrically. So far, gas chromatog- 

 raphy has been more useful in chemistry and in industry than in biology. 

 Probably it will be possible to modify the method for the separation 

 of a wider range of biological compounds. 



SELECTED REFERENCES 



Block, Richard J., Emmett L. Durrum, and Gunter Zweig, A Mantuil 

 of Paper Chromatography and Paper Electrophoresis, 2nd ed. New 

 York: Academic Press Inc., 1958. A comprehensive manual describ- 

 ing theoretical aspects and practical methods. In many cases, sufficient 

 detail is given to allow the reader to perform the operations without 

 further study. Methods are included for almost any conceivable mix- 

 ture of biological materials. Several thousand references to the orig- 

 inal literature. 



Heftmann, Erich, ed., Chromatography. New York: Reinhold Pub- 

 lishing Corporation, 1961. An encyclopedic reference work contain- 

 ing articles on theoretical and practical chromatography written by 

 experts in the field. 



Lederer, Edgar, and Michael Lederer, Chromatography: A Review 

 of Principles and Applications, 2nd ed. Amsterdam: Elsevier Pub- 

 lishing Company, distr. in U. S. by D. Van Nostrand Company, 

 Inc., 1957. Descriptions of general techniques of column chromatog- 

 raphy— with adsorbents and ion exchange materials— and of partition 

 chromatography are given, followed by detailed discussion of separa- 

 tions of various classes of compounds. This is a valuable guide to the 

 literature. 



Strain, Harold H., Chromatographic Adsorption Analysis. New 

 York: Interscience Publishers, Inc., 1945. 



