Table 7. Summary of Countercurrent Separation Elution Methods: Elution-Extrusion Countercurrent Chromatography (EECCC), Back-Extrusion Countercurrent Chromatography (BECCC), and Intermittent Countercurrent Extraction (ICcE).

elution method	phase changea	flow direction change	rotation direction change	comments
classical				highly retained analytes remain in stationary phase
EECCC	single			analytes elute in order of K values
BECCC		single		elution order reverses; some analytes may elute at separate volumes
back-step CCC	twice			a plug of aqueous phase introduced to elute highly retained analytes
dual-mode	single	single		elution order reverses
dual-rotation	single		single	elution order reverses
multiple dual-mode	multiple	multiple		elution order reverses each cycle
ICcE	multiple	multiple		sample loop is in the middle of a single column or between two separate columns

^aPhase change refers to switching mobile and stationary phase.