Abstract: A microscale affinity purification system has a plurality of capillary channels (100) which begin and end in common compartments (110, 120). An introduction cross-capillary channel (130) runs across the capillary channels (100) in a serpentine pattern (136, 138) near one end and a collection channel (140) similarly crosses the capillaries (100) in a serpentine pattern (148, 150) near the other end. A target molecule is introduced from a reservoir (132) which binds to a desired strong ligand in a sample in the capillaries (100). The target-strong ligand comlex migrates through the capillaries (100), is detected at a detector (146), and <collected in a collection reservoir (144).