- 10i+ 



The detection and estimation methods may be based upon any appro- 

 priate property of the separated substances. These properties fall into 

 four principal groups} namely, 



Nuclear properties 

 Physical properties 

 Chemical properties 

 Biological properties. 



Substances separated by chromatography may be described and com- 

 pared by their migration relative to other substances as has long been 

 done with the chloroplast pigments. They may also be compared and des- 

 cribed by their migration relative to the migration of the solvent, 

 which provides the R or the Rp value". In practice, these values are 

 a property of the chromatographic system and of various conditions such 

 as the temperature, the activation of the sorbent, and the presence of 

 impurities in the wash liquid. There will be, therefore, about as many 

 R or Rp values for each substance as there are chromatographic systems 

 for its sorptionj hence only the values for equivalent or identical 

 systems may be compared. 



With all the variable conditions controlled, and with suitable 

 detection and estimation methods, chromatography is one of the most 

 effective techniques for the resolution of mixtures and for the com- 

 parison, description and estimation of the components . 



SUMMARIES 



Keys to the Literature 



The investigations concerning the principles and applications of 



