Patent ID: 8822655

Claim:
A method for concentrating an immunoglobulin solution comprising the following steps: a) providing an immunoglobulin solution with a pH value, with a first immunoglobulin protein concentration, and with a first concentration S + or S − of a buffer substance, b) adjusting said first concentration of said buffer substance to a second concentration S′ and maintaining said pH value, whereby said second concentration S′ is calculated with equation 2 if said buffer substance is a cation/neutral pair or with equation 3 if said buffer substance is a neutral/anion pair, c) concentrating the solution of b) with a tangential flow filtration to a second immunoglobulin protein concentration, wherein equation 2 is S + = - z ⁢ ⁢ P + ( z ⁢ ⁢ P ) 2 + 4 ⁢ ( S ′ ρ ′ ⁢ ( ρ - PM P 1000 ) ) 2 2 and equation 3 is S - = z ⁢ ⁢ P + ( z ⁢ ⁢ P ) 2 + 4 ⁢ ( S ′ ρ ′ ⁢ ( ρ - PM P 1000 ) ) 2 2 with the molar concentration in the retentate of positively/negatively charged solutes (S + /S − ), the charge of the protein (z), the molar concentration (P) and the molecular weight (M P ) of the protein, the density of the solution in the retentate (ρ) and the permeate (ρ′), and the theoretical molar concentration of the diffusible solute (S′).