Classification According to Operating Method

In elution development a small volume of sample is introduced onto the head of the column, and the components are adsorbed onto the stationary phase to various degrees. The solutes are eluted from the column using 

B = components in mixture C is retarded more than B which in turn is more retarded than A. 

Elution chromatography may be subclassified according to the continuity of the mobile phase. Isocratic elution is the term used when the sample is introduced onto the column and eluted from it under the same set of mobile phase conditions. Isocratic elution is the most common way 

To develop a gradient separation, the appropriate strengths for the different eluents must be determined. Often the best approach is to start with a linear binary gradient, beginning with 100% of the weak eluent (e.g., water) and ending with 100% (e.g., acetonitrile, ACN) of the strong eluent. However, the two solutions must be completely miscible at the concentrations used. 

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