Patent ID: 7888476

Claim:
A process for preparing a von Willebrand factor concentrate from a biological fraction containing von Willebrand factor, said process comprising separating said von Willebrand factor by anion exchange chromatography using a vinyl polymer support of a weak base type, said separation comprising the steps of: a) loading the anion exchange chromatographic support equilibrated with a suitable buffer with the fraction containing the von Willebrand factor, wherein said loading is performed at a flowrate at which the anion exchange chromatographic support retains the von Wiliebrand factor; b) washing the loaded anion exchange chromatographic support with an acidic buffer with a flowrate 1.5-2 times higher than that of step a) until the weakly retained contaminants are removed, wherein the pH of said acidic buffer is of pH 3.5- 5.2; c) flushing and equilibrating the chromatographic support with the equilibrating buffer and the flowrate of the step a); and d) eluting the von Willebrand factor concentrate from the anion exchange chromatographic support by increasing the ionic strength of the buffer of the step c).