Preparation of composition comprising two or more antibodies

The present invention relates to a device and a method for preparing a composition comprising two or more antibodies, in particular for preparing at least two antibodies. A method may comprise: providing a cell bearing a nucleic acid encoding the antibody; culturing the cells; collecting the antibody from the culture; and separating the generated antibody from the semi-antibody by ion exchange chromatography (IEX). In certain embodiments, under IEX conditions used, such antibodies exhibit an average deviation of IEX residence time from the residence time of individual antibodies of 10% or less. The invention also relates to compositions of the antibodies thus produced. In certain aspects, the invention relates to compositions comprising 2-10 recombinant antibodies characterized in that under such IEX conditions, the average value of the IEX residence time of at least two of such antibodies deviates from the residence time of individual antibodies by 10% or less. The invention also relates to a composition com