Oligomers that differ by a single repeat unit come off a column almost on top of each other. Here the bands shuttle back and forth between two identical columns, gaining resolution on every pass. Each oligomer is cut into its own vial as soon as it's clean, and the next injection loads automatically. Press play and step through each valve move.
A six-oligomer mixture is loaded onto column A.
This simulates a six-oligomer mixture (n = 1–6) on two matched columns with one isocratic eluent. On pass 1 every band overlaps. Each crossover switch sends the bands through fresh bed. Separation grows with the number of passes while width grows only with its square root, so the slowest bands resolve first. Each one is shaved off into its own vial once it's clear of its neighbour, and the rest keep recycling. The last two are cut with a waste window (W) between them. Tubing is grey while it carries clean eluent and takes the color of whatever band is passing through it. The faint trace shows the whole run.