A method for rapid purification of a blood component from blood is described in which the blood plasma is first separated from the cellular blood elements by any conventional means, such as centrifugation. An affinity cartridge is then activated with a molecule, such as an amino acid, which binds with a blood component such as plasminogen. The separated blood plasma is then passed through the affinity cartridge such that the blood component is retained by the affinity cartridge. Thereafter, the blood component is eluted from the affinity cartridge by passing a buffer solution containing a releasing agent through the affinity cartridge. This releasing agent disengages the blood component from the affinity cartridge. The releasing agent is then separated from the eluted solution by passing the eluted solution through a device, such as an ion exchange, gel filter, or size exclusion device. The isolated plasminogen solution is then concentrated by a factor of from 2 to 10. The separated blood component, e.g. plasminogen, is then converted to plasmin by adding a known amount of an enzyme to the solution from which the releasing agent has been removed.