The recently developed continuous Multicolumn Countercurrent Solvent Gradient Purification (MCSGP) Process has been reduced to a fully equivalent semicontinuous setup with only three chromatographic columns and three gradient pump modules. Actually the 3-column MCSGP unit can even achieve better performance than the original 6-column process due to an additional degree of freedom, that is a different switching time for the "batch lane" and the "interconnected lane." Experimental results for the 3-column MCSGP unit of the purification of an industrial multicomponent peptide mixture containing 46% of Calcitonin on a reversed phase resin are compared with model simulations. It is concluded, that the model is well suited to predict the system behavior and therefore to design its optimal operating conditions.