384 RADIOISOTOPES IN BIOLOGY AND AGRICULTURE 



solutions are dealt with, the direct use of biological fluids may introduce 

 complications. Interfering substances may mask the spots, change their 

 size, or alter the Rf value. In some cases, multiple spots have appeared 

 for a single substance, thus indicating the possible existence of multiple 

 ionic species. These difficulties can often be overcome by use of varying 

 solvent mixtures or, if necessary, the prior removal of interfering sub- 

 stances. In any event, it is always wise to chromatograph known sam- 

 ples in the presence of the same biological substances as contained in the 

 test samples in order to aid in the interpretation. 



GENERAL REFERENCES 



1. Weil, Herbert, and Trevor I. Williams: History of Chromatography, Nature, 166 : 

 1000-1001 (1950). 



2. Zechmeister, L., and L. Cholnoky: "Principles and Practice of Chromatography," 

 John Wiley & Sons, Inc., New York, 1941. 



3. Strain, Harold H.: "Chromatographic Adsorption Analysis," Interscience 

 Publishers, Inc., New York, 1945. 



4. Cassidy, Harold Gomes: "Adsorption and Chromatography," Interscience 

 Publishers, Inc., New York, 1951. 



5. Strain, Harold H., and George W. Murphy: Chromatography, Anal. Chem., 24: 

 50-60 (1952). 



6. Smith, O. C: "Inorganic Chromatography," D. Van Nostrand Company, Inc., 

 New York, 1953. 



7. Wilson, J. Norton: A Theory of Chromatography, /. Am. Chem. Soc, 62: 1583- 

 1591 (1940). 



8. Block, Richard J., Raymond Lestrange, and Gvmter Zweig: "Paper Chromatog- 

 raphy, A Laboratory Manual," Academic Press, Inc., New York, 1952. 



9. Williams, Roger J.: Biochemical Institute Studies. IV. Individual Metabolic 

 Patterns and Human Disease: An Exploratory Study Utilizing Predominantly 

 Paper Chromatographic Methods, Univ. Texas Publ. No. 5109, May 1, 1951. 



10. Toennies, Gerrit, and Joseph J. Kolb: Techniques and Reagents for Paper 

 Chromatography, Anal. Chem., 23: 823-826 (1951). 



10a. Lederer, Edgar, and Michael Lederer: "Chromatography," Elsevier Press, Inc., 



New York, 1953. 

 10b. Block, Richard J., E. L. Durrum, and Gunter Zweig: "Paper Chromatography 



and Paper Electrophoresis, a Laboratory Manual," Academic Press, Inc., New 



York, 1955. 



CITED REFERENCES 



11. Martin, A. J. P., and R. L. M. Synge: A New Form of Chromatogram Employing 

 Two Liquid Phases, Biorhem. J. London, 35: 1358-1368 (1941). 



12. Consden, R., A. H. Gordon, and A. J. P. Martin: Qualitative Analysis of Proteins: 

 A Partition Chromatographic Method Using Paper, Biochem. J. London, 38: 

 224-232 (1944). 



13. Frierson, W. Joe, and John W. Jones: Radioactive Tracers in Paper Partition 

 Chromatography of Inorganic Ions, Anal. Chem., 23: 1447-1452 (1951). 



14. Datta, S. P., C. E. Dent, and H. Harris: An Apparatus for the Simultaneous 

 Production of Many Two-dimensional Paper Chromatograms, Science, 112: 621- 

 623 (1950). 



