" 97 ■= 



recently developed by Martin and James5>°o The sorbent, by contrast, 

 cannot be defined precisely in terms of its chemical composition aloneo 

 Its sorptive properties may depend, in part, upon the method of prepa- 

 ration, upon the treatment after preparation, and upon the degree of 

 subdiTriLsion, The principal interactions of the chromatographic systems 

 frequently employed in solution chromatography are indicated by Figure 

 IV,1. 



Variation of Mixture 



After the effectiveness of the chromatographic prccediore had been 

 demonstrated by the separation of various pigments, the method was 

 adapted to use with many different kinds of substances. These sub- 

 stances have now included all kinds of soluble organic compoionds as 

 hydrocarbons and their various derivatives, numerous labile organic 

 compounds such as carbohydrates, fats, and proteins derived from living 



organisms, and various inorganic compounds including cations, anions, 



7 R 

 and nonionized compo\inds's o 



As virtually all substances may be dissolved, nearly all sub- 

 stances can be examined by chromatographic methodso In this respect, 

 solution chromatography is one of the most widely applicable analytical 

 techniques'^ (See Table IV,IV„) 



An important variation of the mixture is the use of gases and 

 vapors rather than the use of solutions o Gaseous substances and the 

 vapors of substances that boil below about 500° without decomposition 

 may be examined by this so-called gas chromatography5„ This modifica- 

 tion of the technique reduces the dilution of the substances being sepa- 

 rated and facilitates their detection by physical methods, such as 



