Purified proteins are often needed in the basic research laboratory and for diagnostic and therapeutic procedures. An effective technique for protein purification is affinity chromatography, which exploits a specific interaction between a protein and a complementary binding molecule. In this exercise, students isolate albumin from horse serum by affinity chromatography using a column matrix containing a reactive blue dye, which binds specifically to the albumin molecule. They then use electrophoresis to analyze the isolated protein in order to verify the effectiveness of the procedure.