Patent ID: 8772461

Claim:
A method for concentrating a plasma protein of a solution comprising the protein, the method comprising: a) ultrafiltering the solution using a first membrane to form a first retentate solution comprising the protein at a first concentration, wherein the first membrane has a molecular weight cutoff sufficient to retain at least a portion of the protein present in the solution; b) diafiltering the first retentate solution with an aqueous solution using the first membrane to form a second retentate solution comprising the protein at about the first concentration; c) formulating the second retentate solution comprising the diafiltered protein with glycine and adjusting the pH to form a formulated second retentate solution; and d) ultrafiltering the formulated second retentate solution of step c using a second membrane to form a final retentate solution comprising the protein at a second concentration, wherein the second membrane has a molecular weight cutoff of about twice the molecular weight cutoff of the first membrane, wherein the second concentration is greater than the first concentration.